Underwater dungeon . Please help !

[elmuthalleth]

In my next adventure of my campaign , the PC are to explore an underwater dungeon .

Where I can find the rules for movement / combat / weapon damage , etc....
If you want , you can include some cool monsters / spell / traps to include in my dungeon

Thank you !!

 

[daemonslye]

Where I can find the rules for movement / combat / weapon damage , etc.... If you want , you can include some cool monsters / spell / traps to include in my dungeon

Assuming we stick to "core":

Try Dungeon Masters Guide p.92 AQUATIC TERRAIN;

As a DM, I am partial to underdark-aquatic creatures - they have
that special cthulhu-esque quality. Perhaps deep in some idyllic Merfolk
city, a rift has opened and connected to an underdark salt-water
sea populated by kuo-toan cultists and their half-fiend aboleth masters.
They are slowly corrupting the good Merfolk with their dark rites and
foul seeping drug-like brackish water; The PC's, on an important
trade mission, must help the good folk with rooting out the corruption,
stemming the tide of evil, then going into it's very souce to destroy it
and close the rift (kept open via dark magic and pacts with evil elementals).
Encounters with the odd Chuul could be entertaining.

~D

 

[uzagi_akimbo]

non core - the "Seafarer's Handbook" from Fantasy Flight has some extensive /expanded rules on marine combat, and some guidelines as how to plan and run them.

"Creature Collection II" (Swords and Sorcery Studio ) has some wicked marine wildlife for the Scarred Lands (especially the 'Pisceans' ) which might translate well into another setting. Likewise for some stuff from the "Monstronomicon" (Privateer Press ).



As general advice - be careful with "Dispel magic" and like effects, because the PCs will be heavily dependent on magical aid for breathing. Also remember that spell and item use (esp scrolls and potions) will be severely hampered due to vocal difficulties. Bardic music will be almost useless. Ranged fighters, too. Poison use is severly hampered (unless its by some natural delivery system, like a stinger or fang ) 'move silent' and 'listen' will become difficult to judge. Cold spells can be really problematic.

Some ideas (which I have used in underwater settings before) :
- Strong (sudden if possible) currents in tunnels hampering movement, and sucking characters down into some specific directions, like grilles, large moving gears or similar nefarious devices. Especially nasty if coupled with 'darkness'. Whirlpools are mean, too. Consider placing a stationary monster with some reach nearby, grabbing food, ahem 'victims' from the flow at leisure. Directional nets (like those used for lobsters ) can be great fun, too.
- Navigational hazards, especially mazes should be done in all three dimensions (which tends to play havoc with players' perceptions anyway )
- If playing close to the ocean, consider doing tidal rooms, with varying levels of water in them according to the time of day. Or certain doors (valves) will be only open during one phase of the tidal cycle, according to the flow.
- Kelp (carpet, forest, or even a loose drifting bundle) can be real fun, obscuring sight, overgrowing important clues, making people nervous due to unexpected brushing or even entanglement.
- Floors or walls covered with clams and barnacles will make climbing and sneaking difficult and/or painful due to the noise of sharp clam shells being crushed.
- A chamber open to the sea, with massives waves churning in it ( and not much total depth ) can lead to really wicked melee, with combatants constantly being lifted up and lowered, dragged forward and back due to the waves rise and fall , roll and undercurrents (requires some careful planning , but can be a truly meomrable fight )
- Hide things in silt and mud (useful for chambers/areas with little current ), especially fun stuff like trapdoors, monsters or important levers/switches. If the silt gets disturbed.... instant fog cloud ! Even place some large stingray or similar "flat" fish in it.
- In cave systems with some flow of water running through them, include water chutes (nightmarish to climb against the flow ) and even the old standby, a large waterfall.

Hope this helps some