Beneath the Waves: Expanding Tunnels & Trolls into Underwater Adventures

DELVING UNDER THE SEA WITH T&T (& other) RPG

Tunnels & Trolls (T&T) has always encouraged a “go anywhere, do anything” approach to fantasy role-playingmanxgamingsolutions.com. So why not dive beneath the waves? Running an underwater or partially aquatic campaign can open up a whole new world of adventure—from sunlit coral reefs teeming with merfolk to the lightless depths of alien seas. This article provides Game Masters (GMs) with practical tools and advice to expand T&T (especially Deluxe T&T) into underwater adventures. We’ll cover how to build undersea worlds, handle environmental challenges (like water pressure and the pesky problem of breathing), equip your players with the right gear or spells, introduce new monsters of the deep, and even incorporate aquatic kindreds (races) like merfolk or tritons into your game. The tone here is mostly serious and hands-on, but expect a dash of humor (after all, it’s hard not to crack a smile when imagining a dwarf in full plate trying to dog-paddle). Let’s plunge in!
Worldbuilding Underwater Realms
Creating an underwater setting means rethinking your world from seabed to surface. First, decide the scope: is your entire campaign set underwater, or will the players just take occasional dips below the surface? You could design a fully subaquatic kingdom—perhaps an Atlantean city of coral spires and kelp forests—or a coastal region where adventures shift between land and sea. Fantasy Oceans: In a fantasy T&T game, you might have an undersea empire ruled by merfolk or sea-dwelling elves. For example, Trollworld’s lore even includes a cave city called Zmylo, inhabited by humans and sea-elves; much of the city lies underwater, with land-dwelling folk relying on magical water-breathing to visit their aquatic neighbors. Such mixed environments can create fascinating story dynamics, like surface-dwellers negotiating treaties with underwater nations. Science Fiction Seas: If you lean sci-fi, imagine an alien ocean planet where human explorers in high-tech dive suits establish a base on the seafloor, or perhaps a flooded post-apocalypse on Earth. The key is to tailor the environment to your story’s needs.
When designing underwater locales, consider variety. Not all undersea settings are the same: your campaign could include crystal-clear tropical lagoons, murky swamp deltas, deep-sea thermal vents, submerged caverns, or even the insides of a gigantic living kelp maze. Each locale presents different challenges and moods. An enchanted sunken temple might have breathable air pockets (handy for resting spots), whereas the open ocean is a vast wilderness with 3D movement and no easy “walls” – a very different feel from a dungeon corridor. Don’t forget the surface and shoreline too; partially aquatic adventures can involve island hopping, pirate ships, or a mysterious mist-shrouded lake that serves as the gateway to an underwater realm.
Worldbuilding detail enhances immersion. Describe the eerie green light filtering down from above, schools of fish scattering as the party passes, and the distant silhouette of something huge moving in the depths. Think about how underwater civilizations would function: What do they use as currency or technology? Perhaps air-filled domes made from giant shells, or bioluminescent plankton grown in gardens to provide light. How do different races interact? Maybe the merfolk aristocracy of the coral city has an uneasy truce with deep-dwelling tritons over territory. Use real marine science for inspiration too – undersea hydrothermal vents could be the “forges” where aquatic smiths craft weapons, and whale fall carcasses might be like dungeon sites attracting scavenger creatures. In short, approach an undersea environment with the same depth (no pun intended) as any overworld setting, but reimagine everything through a watery lens.
Environmental Challenges Under the Sea
Life underwater isn’t just “dungeons in blue”—the environment itself becomes an active factor in your game. GMs should be prepared to adjust rules or introduce new ones to reflect these challenges. Here are some major considerations:

• Breathing and Drowning: In air, we take breathing for granted; underwater it’s challenge #1. Without magical aid or specialized gear, player-characters must hold their breath. Deluxe T&T doesn’t have exhaustive drowning rules in the core book, but a common-sense approach (inspired by older editions) can work. For example, you might allow a character to hold breath for a short time based on CON or level, then require saving rolls as time stretches on. One fan rule suggests that an adventurer submerged must make a Level 1 CON saving roll in the first combat turn underwater to avoid drowning; a success gives them roughly 2 minutes of action, while failure means they start taking damage and will black out shortly into the next turnstellarcore.net. In gameplay terms, create urgency – ticking down rounds before a breathless hero starts gulping water adds great tension. Without assistance, repeated CON checks could be required each round (perhaps getting harder over time) and any significant exertion might impose penalties. Always telegraph the danger: “Your lungs burn as your time runs out…” is a powerful motivator!
• Pressure and Depth: Water pressure is an invisible killer. The deeper one goes, the more the ocean itself tries to crush you. A realistic approach can be brutal (humans can’t survive deep depths without protection), but in heroic fantasy you can simplify: maybe beyond a certain depth threshold, characters take incremental damage each minute or turn. One set of optional rules gives a guideline: at about 60 feet depth (10 fathoms), start taking 1 point of damage per combat turn from pressure, and +1 point for each additional 60 ft intervalstellarcore.net. So at 120 ft it’s 2 points/turn, 180 ft is 3 points, etc – unless the heroes have a way to resist it. This models how the deep ocean becomes deadly without turning it immediately fatal. You can adjust the numbers for your game’s realism level. Deep-diving creatures (or characters with magic) might ignore these effects. Also consider nitrogen narcosis or the bends if you want to get simulationist – but often it’s enough to say “really deep water = constant damage/hazard” and leave it at that. The flip side is using pressure as a plot device: for example, a wreck full of treasure might lie just beyond the safe depth the players can reach, unless they find a potion of pressure resistance.
• Buoyancy and Movement: Moving underwater is not like walking on land. There’s resistance to every motion. For simplicity, you could impose a reduction in combat movement rates and DEX-based actions for landlubbers in water. Perhaps all physical actions are at -2 “adds” or a -level penalty unless the character has a swimming talent or appropriate magic. T&T Deluxe encourages creative saving rolls, so you might ask for DEX or STR saving rolls to perform agile maneuvers in combat underwater. Armor and heavy gear also affect buoyancy: a character in full plate might literally sink to the bottom (which could be good or bad!). In fact, aquatic beings in T&T lore intentionally avoid heavy armor for this reason – even the seal-like Selkies who swim faster than any human can risk drowning if encumbered by too much metal. Encourage players to think about weight: do they drop their backpack when the shark attacks so they can swim away faster? Swimming on the surface vs. at depth could also differ; on the surface you won’t drown, but you might be swept away by currents or attacked from below.
• Limited Senses: Underwater visibility and communication are tricky. Beyond a few dozen feet (in clear water) it gets dark and blurry. Light does not travel as far underwater, so darkvision or “cats-eyes” abilities might be less effective unless magically enhanced. Colors shift toward blue (ripe for spooky descriptions). At extreme depths, it’s pitch black aside from bioluminescent creatures or whatever light sources the party brings. Speaking underwater is usually a no-go (ever tried talking while scuba diving?). Unless your characters have a telepathy spell or some “aquatic speech” magic, assume that verbal communication is extremely limited. GMs can have fun with this: pass notes to players or encourage them to develop hand signals. Maybe allow a muffled shout in exchange for swallowing a mouthful of water (and risking a drowning check). Spellcasting that requires spoken words might need an alternative method or a higher STRAIN cost unless the caster has a way around it. All these limitations encourage creative problem-solving – a normally simple conversation with an NPC mermaid becomes an elaborate pantomime or writing in the sand.
• Combat Considerations: We’ll discuss weapons in a dedicated section below, but generally combat is altered by the environment. Visibility issues can give stealthy creatures an advantage. Missile weapons have reduced range or accuracy. Swinging a sword feels like waving it through syrup. On the other hand, certain attacks become more fearsome: a lightning spell might electrify a whole area of water (perhaps increasing its effective radius or damage), while fire-based attacks fizzle uselessly into steam unless very powerful. GMs might apply common-sense modifiers: e.g., half damage for slashing weapons underwater, disadvantage or an extra saving roll to successfully hit with ranged attacks, etc. Also consider the vertical dimension: enemies can attack from above or below in a 3D space. This can be thrilling and terrifying – that shark can come up from the gloom beneath your feet. Make use of tactics like ambushes from above or predators lurking below the party. It’s a truly three-dimensional battlefield.
• Other Hazards: Underwater environments come with their own bag of tricks. Strong currents might sweep adventurers off course (a STR roll could be needed to resist). Cold water can sap body heat; in long adventures you might impose fatigue or CON loss if characters don’t find a heat source or magically protect themselves. Aquatic flora can entangle (kelp forests that function like an endless net trap). Air supply isn’t just about breathing – what about keeping flames lit? Normal torches won’t burn; the party will need magical light or modern solutions. Even sound behaves differently: eerie whale-song-like noises could echo and disorient the party as they try to pinpoint a monster’s location. Use these environmental factors to make underwater adventuring feel truly distinct. When players plan a dive, they’ll quickly learn that preparation is key – or else they’ll be in deep trouble.

Finally, magic can mitigate many of these challenges (see next section), and that’s okay. If the wizard casts a spell of water-breathing and a spell of freedom-of-movement, suddenly the team can act almost normally underwater. But even then, there may be moments when those spells fail or run out at a dramatic juncture. Don’t be afraid to remind magically-augmented PCs that the ocean is still dangerous territory. As a GM, balance realism with fun: you want the ocean to feel hazardous enough to be interesting, but not so lethal that the players refuse to ever go there. A few simple house rules and lots of descriptive narration will go a long way to achieving that balance.
Gear, Potions, and Spells for Undersea Survival
Adventurers won’t get far underwater without some tricks up their sodden sleeves. Before sending the party into the briny deep, consider what equipment or magic is available to help them survive and thrive beneath the waves. In a Tunnels & Trolls context, this often means coming up with gadgets and spells that likely weren’t in the original rulebook (after all, classic T&T focuses mostly on dungeons and terrestrial exploits). Here are some ideas to equip your delvers for undersea action:

• Water-Breathing Magic: The most obvious need is a way to breathe. Fortunately, fantasy games have long had solutions for this. In Trollworld’s own lore, inhabitants of mixed underwater cities use “spells or potions for water-breathing” to do business below the waves. As a GM, you can introduce a potion (perhaps “Mermaid’s Kiss Draught”) that grants an hour or two of gill-breathing, or a spell like Aquatic Adaptation that wizards can cast on the party. Deluxe T&T doesn’t list a specific water-breathing spell in its core spells, but it’s very reasonable to homebrew one at an appropriate level. (If you’re using the T&T saving-roll magic system from 7th edition or later, it could even be handled as a Talent or saving roll: e.g. a Level 2 SR on INT to jury-rig a temporary gill enchantment.) The important part is to decide duration and limitations. Perhaps the potion lasts 1d6 × 10 minutes; maybe the spell requires concentration to maintain. You can have fun with flavor too: one GM let his players eat special kelp that oxygenates blood, but it made them constantly hungry after. Another idea is an Air Bubble Amulet – a magical charm that creates a bubble of air around the wearer’s head (classic wizard-diver look!), albeit possibly fragile against attacks. Don’t forget solutions for beyond breathing: a truly prepared aquatic adventurer might also seek potions or spells for pressure protection (Potion of the Whale fat, anyone?) and cold resistance if diving into frigid depths.
• Movement Aids: Swimming speed and agility can be enhanced with the right gear. Simple medieval-fantasy solution: webbed swim fins or gloves (perhaps crafted from giant frog skin) that grant a bonus to swim-related saving rolls. More advanced: enchanted Boots of Buoyancy that let you adjust your buoyancy at will, or a Cloak of the Manta that turns you into a ray-like form for effortless gliding. In a technology-rich or steampunk setting, you might introduce clockwork propeller packs or flipper-like mechanical boots. Even something as straightforward as rope can be a lifesaver underwater – a party can tether themselves together to avoid getting separated in a strong current, or use a rope line to find their way back out of a maze-like reef (like an underwater version of a dungeon breadcrumb trail). Magic can assist movement too: spells that grant water-borne flight (essentially underwater levitation) or that calm turbulent water around the party (preventing currents from throwing them about). A creative wizard might adapt an Airy Cloud spell to work as an underwater jet stream pushing characters in a desired direction. Be open to player ingenuity here – they may ask, “Can I cast my usual Speed spell underwater to swim faster?” Depending on your style, you might allow it with a penalty or require a separate aquatic version of the spell. The goal is to give non-aquatic characters a fighting chance to maneuver with those nimble merfolk.
• Tools and Weapons (Waterproofing): Standard gear may need modifications. Oil lanterns won’t stay lit (unless you have a magical continual light). Glowsticks or bioluminescent fungus harvested from a cave could replace torches. Crossbow strings need to be waxed or waterproofed. Scrolls and spellbooks could be sealed in waxed leather cases (imagine the panic on a wizard’s face when his only copy of a spell begins to dissolve in saltwater!). Encourage players to think ahead: if they know an underwater quest is coming, savvy adventurers might stock up on sealed waterproof containers, harpoons, and maybe a pet diving bell. If they don’t think of it, an NPC mentor or vendor could offer these items (“Old Captain Fishtooth sells you a diving kit – essentially sheep bladder balloons for buoyancy and a 50-foot hose attached to a bellows on your boat to pump air down. Primitive but it works… unless a fish bites your air hose.”). In more primitive settings, a hollow reed might suffice for breathing in shallow water, but that won’t help you in the open ocean. As GM, you can decide how realistic to be. It’s perfectly fine to say “standard leather armor becomes waterlogged and very hard to swim in” to nudge players toward shedding heavy gear, even if real-world leather isn’t that heavy. A note from earlier editions: some spells can outright negate drowning or pressure damagestellarcore.net – if such magic is accessible, players may lean on it, but remember magic can fail at inconvenient times!
• Specialized Equipment: Beyond the basics, think of interesting items or treasure that relate to underwater play. Maybe Wand of Aquatic Speech – when activated, it creates vibrations that allow speech underwater for a short time (essentially a magical underwater loudspeaker). Or Neptune’s Trident, an artifact that not only serves as a weapon (3-pronged spear) but also lets its wielder command small sea creatures or part water like Moses on a minor scale. Swimming potions could be a thing: a dose that temporarily grants the swimmer strength of a dolphin or the tail of a fish. In one sci-fi-flavored campaign, we gave the party an “aqua-lung” device (inspired by early diving suits): a backpack with air and a helmet, but it was clunky and limited their mobility (reflected by a DEX penalty). If your game strays into the high-magic or high-tech, you could even provide a small submersible vehicle – perhaps a gnomish clockwork submarine or an enchanted giant sea-shell that ferries the party. Such vehicles bring their own challenges (e.g., how to battle monsters while inside a cramped sub, or what to do if it springs a leak!). They can, however, alleviate a lot of survival concerns and shift the gameplay to managing a vessel.

In summary, make sure the players have some way to survive the environment, or at least a plan for it. Underwater adventures tend to require more pre-planning than ordinary ones. GMs might even present the players with a “shopping list” or hints beforehand: an old sailor they consult could enumerate, in character, “Ye’ll be needin’ breathin’ potions for them depths, and a way to see in the dark down there, not to mention something to keep the chill off yer bones.” This not only foreshadows the challenges but also adds to the immersion (the players can’t say they weren’t warned!). Equipped with the right gear and spells, your terrestrial delvers might just become as comfortable under the sea as they are on land… well, almost.
Monsters of the Deep: New Challenges for Aquatic Campaigns
What’s an adventure without monsters? The oceans (of Earth or any fantasy world) are full of creatures strange and terrifying – and that’s before you add fire-breathing sea serpents or alien leviathans into the mix. When expanding T&T underwater, a GM should sprinkle in some new monsters or adapt old ones to the marine environment. Here are a few ideas, ranging from fantasy classics to sci-fi horrors, to make your undersea campaign come alive with danger:

A 16th-century woodcut depicting hideous marine monsters (a “water devil” and a giant sea-horse). Imagination has long populated the deep with fearsome creaturescommons.wikimedia.org.

• Aquatic Dragons: Dragons are a staple of fantasy, and there’s no reason they can’t rule the seas as well as the skies. An aquatic dragon might resemble a colossal sea serpent or a wingless dragon with fins. In T&T lore, dragon forms vary widely – some even look like alligators or dinosaurs, which lends itself perfectly to a water-dwelling “dragon.” You can treat an aquatic dragon as a powerful serpent that can still breathe something nasty – perhaps instead of fire, it boils the water with superheated steam or spits jets of corrosive acid. Combat with such a beast could involve it coils around characters or even around a whole ship. A fun twist: because sound travels well in water, the roar of an aquatic dragon might stun divers in the vicinity (sonic damage!). Also consider dragon intelligence: an ancient sea-dragon could be the cunning mastermind behind attacks on coastal shipping, sending its lesser shark and eel minions to soften targets. For a science-fiction angle, an “alien leviathan” could fill a similar niche – e.g., a titanic extraterrestrial marine beast that the players might awaken or encounter in an off-world ocean. The Leviathan of the alien seas might not breathe fire, but perhaps it emits EMP bursts or has bioelectric pulses like a colossal electric eel, knocking out equipment and subs.
• Alien Leviathans and Mega-Fauna: Speaking of leviathans, the deep ocean is the perfect place for really big monsters. Kraken, giant squids, enormous whales – these can be adapted or invented to challenge even high-level parties. An alien leviathan could be a creature so large the players initially think it’s just part of the landscape (imagine exploring a reef that starts moving because it’s actually the back of a gargantuan beast!). Sci-fi examples include things like the huge creatures in movies such as The Abyss or Sphere, or the legendary sandworm-like Leviathans in some space opera oceans. For fantasy, you might have the “Father of All Sea Serpents” as a unique one-of-a-kind monster. Mechanically, such beings might be beyond fighting in a toe-to-toe battle – instead, an encounter might revolve around surviving or escaping it. For instance, a scenario where the party is swallowed by a leviathan and must find a way out from inside (a classic Jonah-in-the-whale situation that doubles as a dungeon crawl in a creature’s belly!). If you do want a leviathan fight, emphasize the environment: perhaps the only way to hurt it is to lure it into underwater lava vents or trick it into fighting another giant creature. Also, leviathans don’t need to be solitary – a school of giant manta rays or a migration of colossal jellyfish can present interesting non-traditional “monsters” that aren’t evil, but are dangerous obstacles simply due to their size or poisonous nature.
• Coral Golems and Living Reefs: One of the more unique threats in an underwater fantasy is the idea of the environment itself coming alive. Enter the Coral Golem. Picture a stony conglomeration of corals, shells, and shipwreck debris, animated by a sea witch or nature spirit. It might lie motionless, indistinguishable from a normal reef formation, until unwary adventurers disturb the area – then the reef itself lurches up, forming a hulking humanoid shape of coral arms and stone. Coral golems could be slow but almost impervious to normal weapons (coral is hard!), and might have abilities like shedding clouds of stinging coral polyps (treat as a cloud of irritant or poison) or breaking apart and reassembling (maybe when you “kill” it, it shatters into several smaller coral critters). Such a monster emphasizes the alien nature of the underwater world – it’s not just fish and eels down there. As guardians of sacred underwater sites, coral golems would make excellent protectors of sunken temples or druidic circles under the sea. And yes, fighting one underwater means that every missed swing might chip off bits of coral, potentially damaging gear or cutting characters (coral cuts – ouch!). For a sci-fi spin, you could reskin this as a nanite coral colony, a technological construct that behaves similarly – maybe an alien tech that has merged with coral and defends an area like a drone hive mind.
• Aquatic Humanoids (Friends and Foes): Beyond the well-known merfolk (we’ll discuss playable aquatic races in the next section), there are plenty of underwater “peoples” that can serve as adversaries or allies. Classic enemies include shark-men or fish-men (D&D players might think of Sahuagin or Kuo-Toa). In T&T, you could simply describe these as a new kindred or as monsters with appropriate Monster Ratings. For instance, sea goblins or sea uruks could be a thing – brutish green-skinned raiders adapted to the water, perhaps with gills and webbed hands. In Trollworld’s history, there are even accounts of “sea uruks” riding flying serpents in coastal assaults, so the concept of aquatic or amphibious orcs isn’t far-fetched. These underwater humanoids might use tactics like attacking en masse at night from the water, dragging characters into the depths. Equipping them with nets, tridents, and tame sea creatures (shark pets?) makes for exciting encounters. On the friendlier side, consider Nereids or water spirits – maybe a neutral fae creature that might help or hinder the party depending on how it’s treated. Crocodilian Lizard-Men can add a swampy flavor to shallow water adventures (T&T’s Deluxe mentions aquatic lizard folk in one region, described as intelligent crocodiles who will literally eat anything that talks – clearly a potential monster encounter). Lastly, don’t forget undead: the drowned corpse that rises to pull the living underwater is a classic horror element. Drowned zombies or ghost pirates haunting a wreck could provide a horror element amid all the fishy foes.
• Mythic and Science-Fantasy Encounters: The sea has inspired countless myths – feel free to draw on them. A kraken (giant squid/octopus) attacking a ship or strangling divers with tentacles is a must for at least one encounter. Sirens or merfolk sorcerers might lure adventurers into traps with enchanting songs that somehow carry through water (maybe magically). A kelpie (a shapechanging water horse) might prey on those near the shore, pretending to be a lost steed. On the science fiction side, you could incorporate things like biomechanical creatures – e.g., a cybernetic fish swarm that’s actually a self-replicating alien weapon. Underwater constructs from an ancient civilization could also appear: picture an undersea dungeon that has guardian constructs like clockwork crabs or aquatic drones still patrolling its halls. If your campaign involves gods or deities, perhaps an avatar of a sea god – like a colossal humanoid made of water – confronts the party. The range is huge; the ocean is essentially the final frontier on many worlds, so fill it with wonders and terrors. Encourage your players to use different tactics against these monsters. In one fight, brute force might work (harpoons into the kraken!). In another, they might need to solve a puzzle (figuring out how to placate an angry water spirit by retrieving a lost pearl). Underwater battles can be as varied as surface ones, as long as the monsters have unique twists that leverage the environment.

When introducing these new monsters, give a nod to how they live underwater. Do they use ambush tactics (hiding in sand or coral until prey passes)? Do they hunt by smell or vibration (making stealth difficult)? A monster might create hazards like swirling sediment to blind the PCs or flee into tight crevices where larger characters can’t follow. All these elements make underwater monsters memorable. And yes, you can have a bit of humor too – maybe the party’s first “monster” is a territorial dolphin that keeps head-butting the dwarf, or a tiny fish that steals something shiny from them leading into a comic chase. Not every encounter has to be life-or-death; a lighthearted scene with curious sea creatures can break up the tension (perhaps your group of delvers finds themselves followed by a goofy baby sea dragon that thinks the party’s wizard is its mama!).

In summary, populate your aquatic world with a mix of the familiar and the unexpected. For every standard giant crab, throw in a coral golem or for every school of mundane barracuda, imagine a ghostly phantom ray that drains life force. Players will quickly learn that under the sea, they can’t assume anything is harmless. As a GM, you have the opportunity to create truly fresh encounters that players will remember – after all, it’s not every day you get attacked by a barnacle-encrusted zombie pirate riding an undead shark (unless you really make underwater campaigns your thing!). Let your imagination swim wild, and your players will love (and fear) the results.
Aquatic Kindreds: Merfolk, Tritons, and Other Undersea RacesOne exciting aspect of underwater adventures is the chance to introduce aquatic intelligent races into your game – and even allow players to play them as characters. Tunnels & Trolls has always been flexible with character kindreds (races), and Deluxe T&T includes a few aquatic or amphibious folk in its bestiary. Here we’ll discuss how to use aquatic kindreds in your campaign, with a focus on conceptual descriptions, role-playing tips, and any mechanical tweaks needed to fit them into T&T’s system (while keeping things compatible with other RPG systems too).

• Merfolk: The classic half-human, half-fish people of the sea. In Deluxe T&T, merfolk are indeed present as a kindred option, and they come with some important caveats. Physically, a merfolk character has the upper body of a humanoid and from the waist down a powerful fish tail when in the water. Notably, T&T’s lore gives merfolk the ability to shapechange to walk on two legs on land, but they don’t suddenly become “normal” humans – even in legged form “no one would mistake them for anything but a fish-person” due to their scaly skin, webbed digits, and gurgling speech patterns. Merfolk have both gills and lungs, meaning they can breathe water or air, but they hate being away from water for long. A merfolk on land will weaken over time – the rules mention they become feeble if dry for too long and must keep their skin damp. As a GM, you can represent this by a gradual penalty to STR or CON each day away from water, for example. Role-playing a merfolk means embracing that fish-out-of-water theme: maybe your merfolk wizard constantly carries a damp cloak or has a portable tub to sleep in. In underwater scenes, however, merfolk shine (literally, if they have shiny scales). They are in their element, gaining full mobility and no breathing issues. In combat, merfolk favor small, light weapons like knives and spears and avoid heavy armor under the sea – logically, a merfolk warrior would fight with a trident or harpoon rather than a greatsword. Mechanically in T&T, you might give merfolk characters bonuses to DEX or SPD in water and penalties on land. Deluxe T&T’s attribute multipliers for merfolk (if you use them) reflect some of this; you can also allow a merfolk PC to take a Talent like “Expert Swimmer” for free. For a merfolk’s personality, consider their culture: perhaps they come from an underwater kingdom with different values (maybe less concept of personal property, making them seem aloof or naive to surface-dwellers, or a superstition about fire since they rarely see it). A merfolk in a party of land adventurers can provide comic relief (“Why do you humans drink water? You’re supposed to breathe it!”) as well as useful skills for aquatic missions.
• Tritons: Often depicted in myth and D&D lore as sea-dwelling humanoids (sometimes portrayed as male counterparts to mermaids or as an altogether separate race of aquatic humanoid warriors). In your T&T campaign, Tritons could be a branch of merfolk or sea-elves that always have a humanoid form (with legs) but are fully adapted to life underwater. Think of them as amphibious humans with perhaps blue-green skin, gills on their necks, and maybe fins along their arms or legs. They might not swim quite as swiftly as a mermaid’s tail, but they don’t suffer the shapechanging limitations either – a triton can stride on land from day one, albeit probably still preferring moist environments. Role-play wise, tritons could be the noble guardians of the sea, often depicted carrying tridents and riding sea horses or dolphins. They might have an inherent cultural rivalry with merfolk (who see tritons as uptight and militant, whereas tritons see merfolk as too capricious). In terms of adapting to T&T mechanics, you could treat a triton much like a humanoid kindred with a natural talent for swimming. Give them a minor bonus in water and perhaps a minor penalty in very dry climates (maybe their skin dries and it’s uncomfortable, but not as debilitating as a merfolk’s weakness). Since Deluxe T&T doesn’t list “triton” explicitly, you have freedom to define them. For balance, perhaps no stat multiplier changes at all, just the special ability to breathe water/air and swim well. That alone is a huge advantage in an aquatic campaign, so you might offset it by, say, making metal armor corrode quickly on them or some quirk. A triton PC would be great for a player who wants to be from the underwater world but not deal with having a tail or mobility issues on land. In a multi-genre game, you could even have “triton aliens” on a water planet – it’s a concept that ports well to sci-fi.
• Selkies (Seal-Folk): Selkies are a wonderful addition for a more folkloric vibe. These are creatures from Celtic myth: seals that can shed their skins to become human on land. Deluxe T&T includes selkies as a kindred, describing them as mammalian water-dwellers who cannot breathe underwater (unlike merfolk) but are excellent swimmers and divers. A selkie character essentially has two forms: in the water, they usually don a seal shape (which lets them swim fast, see in dim light underwater, and dive deep while holding breath a long time), and on land they appear as human – except for notably large dark eyes and a certain sleek quality to their hair/skin. The crucial bit of selkie lore: they have a seal skin (pelt) that they must have with them to transform. T&T notes that selkies are vulnerable in that they need to keep their seal skin safe – if it’s stolen or lost, they’re essentially trapped in human form. This can make for excellent plot points (perhaps an evil pirate has been collecting selkie skins to blackmail their owners). In role-play, a selkie might be torn between two worlds, enjoying companionship with land-dwelling friends but always hearing the call of the sea. They likely have an “uneasy relationship” with merfolk (imagine the cultural divides between a fish-person and a seal-person). In game, since selkies can’t breathe water, they face many of the same challenges as human characters when adventuring underwater – except they excel at those CON rolls for holding breath and can out-swim just about anyone when in seal form. As T&T notes, selkies favor light weapons and little armor in water (you ever see a seal try to wear chainmail? No, and you won’t). A selkie PC could be a scout or rogue-type, slipping into the water to scout ahead in seal form, then coming back to report to the party in human form with a shake of seawater from their hair. Encourage selkie players to play up the fun – maybe they bark or clap like a seal when excited, or have a love of fish cuisine that grosses out their comrades. Mechanically, you might let a selkie switch to seal form at will (assuming they have their pelt on them) which grants bonuses to swimming and stealth in water, but perhaps in seal form they can’t use hands or weapons effectively. Switching forms might take a full combat round or two (so they can’t just instantaneously dodge an attack by turning into a seal).
• Sea Elves (Aquatic Elves): Many fantasy settings have a variant of elves that dwell beneath the sea. Trollworld itself references sea-elves mingling with humans in underwater cave cities, so they exist in T&T’s universe. Sea-elves could be very similar to land elves in stats – graceful, intelligent – but adapted to water life. Perhaps they have subtle gill slits and webbed fingers, and their skin might have a slight shimmer or algae tint. They likely live in elegant subaquatic cities sculpted from coral and pearl. As player characters, sea-elves wouldn’t be too mechanically different from regular elves aside from the ability to breathe underwater and swim. Culturally, they might be aloof or even xenophobic toward surface dwellers (“the landfolk… so clumsy and short-lived”). They might use dolphin messengers or ride sea turtles as mounts. If you include sea-elves as an option, decide if they are fully amphibious or if, like merfolk, they get uncomfortable out of water. Given that humans in Zmylo needed potions to visit the sea-elves underwater, it stands to reason sea-elves themselves handle both environments fine. Perhaps their magic is attuned to water (water elemental spells, illusions involving mist and currents, etc.). For a player, a sea-elf offers a chance to play the quintessential “inscrutable elf” but in an aquatic context – maybe your sea-elf warrior-princess is on a mission to find allies among surface dwellers against a rising threat in the deep. One thing to consider: what about communication? If sea-elves (and merfolk, tritons, etc.) can breathe water, do they have a spoken language underwater? Possibly a form of sonar-like dolphin speech or a sign language. T&T doesn’t detail this, but you can decide for your world. It could be fun to say, “Sea-elvish is a beautiful flowing language of gestures and high-pitched tones – nearly unpronounceable in air.” So a sea-elf PC might have an unusual accent or prefer telepathic communication spells when available.
• Others (Gill-Men, Aquatic Dwarves, etc.): The above are the major examples, but your imagination is the limit. Gill-Men (think “Creature from the Black Lagoon”) could be a less sophisticated kindred – perhaps an NPC race of amphibious humanoids that aren’t quite as advanced as merfolk or sea-elves, but one might join the party (maybe a curious young gill-man looking for adventure beyond his swamp). Amphibious or water-adapted versions of other races could exist: an aquatic dwarf clan that lives in underwater caves, holding their breath for astonishing periods and claiming pearls instead of gold. Or frogfolk (like bullywugs in D&D) in marshes that could also operate underwater to an extent. If your campaign goes to alien seas, you could introduce completely non-humanoid intelligences – perhaps a playable character is a psychic cephalopod (octopus-person) or a sentient coral colony piloting a construct. Those might be far-out ideas, but they illustrate that “aquatic kindred” doesn’t have to stop at the familiar mermaid. Always balance these concepts with party dynamics: if everyone else is human and dwarf, the player who picks “giant intelligent jellyfish” might have a hard time fitting in traditional scenarios. It’s often easier to stick with humanoid-shaped races for player characters. NPCs, however, can be as weird as you like – the undersea tavern could have a jellyfish bartender, a crab-person bouncer, and a pair of lobsterfolk arguing in a corner. Why not?

Mechanics and Compatibility: In Tunnels & Trolls, introducing a new kindred usually means assigning attribute multipliers (e.g., merfolk might have a multiplier that boosts DEX and SPD in water, but perhaps lower STR on land). Deluxe T&T has a table for kindred multipliers which you can use as a guideline. For instance, if a merfolk is notably weaker on land, you could say their STR is at 0.5 × rolled value (half) when out of water. But you might give them ×2 STR in water due to the tail propulsion. Rather than get too bogged down, you can also just role-play these differences and use simple saving roll modifiers. The beauty of T&T is its simplicity and the “rulings over rules” ethos. So, ensure everyone at the table understands any special abilities or limitations a water-race character has. If you’re blending with other systems, translate those traits accordingly (for example, in D&D terms: a merfolk might have a swimming speed of 40 ft but a disadvantage on attack rolls on land due to awkwardness).
Role-play Tips: Encourage players with aquatic PCs to think about how their character views the world. A merfolk might be fascinated by fire (something they can’t use underwater) and terrified of deserts (“it’s like an ocean with no water!?”). An aquatic elf might look down on humans for their inability to breathe underwater, akin to how elves sometimes condescend about human’s short lifespans. There’s also room for humor: perhaps the triton has very literal humor (“I don’t get your land idioms – ‘fish out of water’? Sounds dreadful.”). These differences can be a source of intra-party fun as well as plot points.
Inclusion of aquatic kindreds adds richness to your underwater campaign. They turn the setting from “we humans visiting a hostile alien world” into “a living world with its own people and politics.” Maybe the players even switch between land-dwelling and water-dwelling party members depending on the mission (one session you run the merfolk ranger and sea-elf mage exploring an ancient reef, next session your human warrior and dwarf go on a surface quest to get supplies). If managed well, aquatic kindreds can be as balanced and playable as any other race, and they give your campaign a fresh flavor that sets it apart from standard fantasy fare.
Weapons and Combat Adaptation UnderwaterWhen swords and sorcery meet the sea, expect some changes in how combat works. Weapons that were perfectly fine for slaying trolls in a dungeon behave very differently beneath the waves. As a GM, you should address this upfront so players can arm themselves appropriately (and avoid that comical moment when the heavily armed knight jumps into the water and promptly discovers his sword might as well be a butter knife in the surf). Here’s a rundown of considerations and ideas for adapting weapons and fighting techniques to underwater adventures:

• Slashing and Bludgeoning vs. Piercing: In general, thrusting/piercing weapons are king underwater. A trident, spear, harpoon, or even a slim dagger can be jabbed forward with relative ease, slicing through water toward a target. In contrast, wide slashing attacks (longswords, battleaxes) encounter a lot of drag, and swinging a mace or hammer underwater is like trying to swing in slow motion. Many game systems (like D&D) impose disadvantage or reduced damage for such weapons underwater; you can implement a similar penalty in T&T. Perhaps rule that swords and axes do half their rolled damage underwater, or better, encourage players to swap to more suitable arms. The Deluxe T&T lore supports this: aquatic peoples themselves choose spears and knives as their weapons of choice. A merfolk gladiator with twin short spears is much more plausible than one swinging a huge claymore. For bludgeoning weapons, you might say anything heavier than a small club is nearly unusable below (try swinging a warhammer in a pool – you won’t be happy). Some GMs might allow a strength save or penalty (“you can use your greataxe, but your DEX is considered 5 for attack purposes due to water resistance”). Simpler is just to strongly hint that players carry a spear or dagger for these situations.
• Ranged Weapons: Projectiles are problematic underwater. Arrows from bows tend to lose momentum almost immediately upon entering water, unless shot from very close and very powerful bows – not to mention bowstrings and water don’t mix well. Crossbows fare a bit better due to the force of the bolt, but still, effective range will be a fraction of normal. Thrown weapons like spears or javelins can work at short ranges, essentially like an underwater harpoon. One interesting compromise: use a spear gun or harpoon launcher if your tech level allows (even a simple spring-loaded device could be gnomishly engineered in a fantasy setting). These would give a bit more range and punch. Otherwise, expect most underwater combat to be up close and personal. If a player insists on using a bow, perhaps allow it only if they are in an air pocket or air-filled cave shooting out into water (and still, range will be tiny). Crossbow users might waterproof their crossbows and use special quarrels. As a rule of thumb, you could say all missile attacks have -4 to hit and quarter their usual range underwater (unless specifically designed for it). This encourages players to get into the spirit of underwater melee or find magical solutions (like spells, or maybe trained attack dolphins acting as their “missile weapons”!). Speaking of which, nets are an excellent ranged (or thrown) weapon underwater – they were meant to be used in water by fishermen and can entangle foes just as well as fish. Consider allowing a net throw to immobilize or at least impose big penalties on a target who fails a saving roll to resist. Nets make great non-lethal options too if the party is trying to capture an aquatic creature or enemy alive.
• Specialized Underwater Weapons: You’ve likely mentioned tridents a few times – and indeed, the trident is iconic for underwater combat. In game terms, a trident is similar to a spear (maybe +1 to damage or easier to catch/entangle things with due to the prongs). Other specialized arms include barbed spears/harpoons – these could be spears that do ongoing damage once they impale (the barb makes them hard to remove; perhaps on a hit, the target takes normal damage and then must make a STR/LUCK roll each round or take additional 1d6 as the barb tugs, until they take a round to yank it out, causing even more damage). It’s gruesome, but that’s how whalers did it. Daggers and short swords (gladii): Romans used short swords effectively underwater (historical tidbit: they had divers sabotage enemy ships). So in your fantasy, a “boarding knife” or short sword is acceptable for close quarters. Polearms with reach (like a trident or spear) are very useful since moving in close is harder underwater – having an extra 5 feet of reach can mean the difference between striking a shark and being bitten by it. Cutting weapons aren’t entirely useless; small hand axes or hatchets could work for hacking through kelp or ropes, but as a main weapon they lag. If you want a creative twist, allow an enchanted cutting weapon: e.g., a “sword of the mariner” that creates a thin air sheath around itself so it slices through water normally (an expensive or rare item, no doubt). This gives fighter-types something to aspire to – retrieving Neptune’s own cutlass that will swing true underwater. Another interesting weapon is the dueling fork or trident dagger – basically a smaller trident used in off-hand to parry (there is a historical weapon like a trident parrying dagger). An enterprising rogue might dual-wield those underwater, which certainly paints a picture.
• Adapting Fighting Styles: Combat tactics should adapt along with weapons. Grappling becomes both easier and harder underwater – easier in that weight and momentum are different (a weaker opponent might manage to grapple a stronger one with clever use of buoyancy), harder because everything is slippery and three-dimensional. If players try grapple or unarmed combat underwater, perhaps allow it but with some DEX disadvantage unless they have a specific training or anatomy advantage (e.g., an octopus-man grappling you is a nightmare scenario because tentacles excel at that). Also consider shield use: a shield can still block in water, but large shields could be cumbersome. Maybe a small buckler is fine, but a tower shield is nearly impossible to drag around underwater. Poison on weapons might get washed off unless it’s a specialized aquatic poison. On the other hand, some real sea creatures are poisonous; maybe PCs can harvest pufferfish toxin to coat their harpoons – it won’t wash off immediately because it’s naturally slimy and water-stable. Encourage ingenuity: the fighter who normally swings a two-handed sword might switch to a one-handed trident and a net for entangling, essentially changing from a slashing-heavy style to a control-and-thrust style. Archers might take on a support role, maybe using a crossbow with rope-tied bolts to deliver messages or create distractions rather than sniping kills (for instance, firing a bolt attached to a line with a lit flare (magical light) to illuminate an area). Magic users in combat might use more area of effect spells since precise aiming is tough underwater – for example, a fireball might just heat the water into a scalding cloud (still effective if you flavor it right), and lightning spells could automatically hit everything in water if you’re not careful (including allies!).
• Armor and Protection: We touched on this earlier – heavy armor is a liability underwater. Not only for sinking reasons, but mobility. Historically, divers in armor (yes, it’s happened – there are accounts of medieval armored divers) found it extremely difficult. In T&T terms, you might reduce the protective value of armor that’s waterlogged or say that anyone wearing armor above a certain weight class suffers continuous Combat Adds penalties or loses combat rounds struggling. This doesn’t mean characters must strip to their skivvies; there are alternatives. Light armor or specially made gear is fine – e.g., a suit of scaled leather armor treated with oils might actually be thematic for a merman knight. Magical protections like rings or spells can substitute for plate mail. One humorous yet practical item: fish-scale armor (literally armor made from giant fish scales) – it’s naturally at home in water. Maybe the fabled city of sea-elves forges scale armor from dragon turtle scales that provides good defense with neutral buoyancy. Shields, as mentioned, should likely be small if used at all. Another angle: since maneuverability is crucial underwater, no armor but high DEX could be a viable approach (much like how real-life divers rely on agility). If a player insists their warrior stay in armor, perhaps let them but describe how they effectively walk on the seafloor rather than swim (which could work in some scenarios – a “walking tank” slowly trundling on the ocean floor, immune to bite attacks on the parts covered in steel, but vulnerable if knocked prone into a trench or if something attacks their few exposed gaps). In a way, this could be balanced: heavily armored fighters become like walking submarines – slow, relatively protected, but once something bypasses that armor (say, a giant eel wraps them up or an enemy grapples and finds a joint), they’re in trouble and they’ll sink fast if there’s a drop-off. It might be worth a few laughs (imagine the party’s knight stuck upside down in his armor underwater like a turtle), but it also can illustrate why most prefer lighter gear below.
• Explosives and Firearms: Depending on your campaign tech, these might or might not be present. Black powder weapons do not like water. You can pretty much rule out guns unless they are somehow sealed and you have rules for firing in air bubbles, etc. If you’re playing a more modern or sci-fi underwater scenario, harpoon guns, spear guns, or torpedo-like devices replace firearms. Explosives underwater have different effects: concussive shockwaves carry farther (stunning fish at a distance). A clever party might use a small blasting charge not to fragment-damage enemies, but to stun them with the shock (you could have it force a saving roll vs CON for all nearby creatures or be stunned). One classic trope is using an explosion to blow open a sunken ship’s hull or scare off a monster. Just be mindful of physics – in a closed space underwater, an explosion will reverberate brutally (possibly hurting the PCs more than the monsters if they’re not careful). Magic “fireballs” as mentioned would likely become steam bombs underwater; you could adjust damage or radius as you see fit, but don’t let players argue a fireball wouldn’t work at all – magic can handwave the physics if needed (maybe it creates a momentary pocket of superheated plasma that then collapses into a shockwave). On the flip side, spells involving air might actually create dangerous cavitation or pressure effects – lots of fun possibilities to explore for the creative spellcaster.

To wrap up, the motto for weapons and combat underwater is: adapt or perish. Players should be encouraged to think about their loadout before diving, and you as GM should be consistent and fair in applying any modifiers due to water. It might help to summarize your house rules on underwater combat ahead of time (e.g., “Alright folks, remember – spears, tridents get full effect; slashing weapons half damage; ranged weapons very limited; heavy armor will slow you terribly,” etc.). After a fight or two, it’ll become second nature. And when in doubt, lean into narrative description: if a player tries something questionable like swinging a flail, instead of just saying “it misses,” describe how “you swing the flail, but the water resistance almost yanks it from your grasp and it crawls through the water without momentum – the shark easily dodges the sluggish attack.” Descriptions like that reinforce why certain tactics shine underwater and make successes feel earned (“your thrusting swordfinds its mark with far more ease than a slash would – good thing you adjusted your fighting style!”). By adjusting combat expectations, you’ll ensure underwater battles are challenging in a fresh way, but still fun and winnable with the right strategy.
Conclusion: Diving Deeper (Further Reading & Future Ideas)Running an underwater Tunnels & Trolls adventure can be a richly rewarding experience. It forces everyone to think outside the box – the GM gets to flex creative muscles designing aquatic locales and strange encounters, and the players have to overcome challenges far removed from a standard dungeon crawl. We’ve only just scratched the surface (or perhaps the seafloor) in this guide. There are countless directions to explore from here. For example, you might expand into underwater economics and politics (merfolk vs. sea elf rivalries, trade between surface and underwater cities), introduce undersea vehicles or mounts (giant sea-horse chariots, anyone?), or develop a whole campaign arc around a lost sunken continent that players must help rise (or keep sunk!). The Deluxe T&T rules give you a solid foundation, and because T&T is inherently flexible, you can easily incorporate these underwater elements into other systems as well – the ideas here are system-agnostic at heart.

Where can I buy Tunnels & Trolls?

Ok the easiest way is to buy from Wargame Vault and full range of Flying Buffalo and other publishers (watch that space for us!) is available there. Here is the Flying Buffalo Page.