underwater adventures

[Fitz]

OK, in the campaign i usually run, i am currently planning the 2 dungeons the party needs to go through to get to the final encounter, 1 is planned to be a fire-element themed dungeon which is fairly easy for me to set up, the other is planned to be underwater. i have Stormwrack to help with, but i am after advice on a) ideas for challenges change in difficulty due to being underwater, and b) what items the players might want to help them through this area?
the party has a Duskblade (Glaive combat ref build) a Rogue and a scout, a Cloistered cleric (healer/buffer) a Dragon Shamen (gold dragon) a Bard/Swashbuckler, and a Fighter (greatsword, wp spc etc)
so not too much arcane support.

Fitz

[de-trick]

1) figure how they will breath underwater, and then it gets easier

[Funkyodor]

Non-corporeal creatures and undead are good because they can be easily explained in underwater sections.

Quick current to a Waterfall if someone triggers the "Flush" button of the toilet bowl trap.

Giant Shark in a darkened area, if they have to travel underwater to get to the dungeon you can use the Jaws idea and have it a recurring villain.

Oozes, Molds, etc.

Just make sure they can get reliable access to Underwater Breathing and some light source.

[Prometheus]

Boiling water makes for a nice trap or puzzle - they should be able to get fire resistance if tehy survived the fire dungeon, so this is just some flavor.

Funkyodor has good creature selections, but just as the monster manual does to Trolls/Scrags, and Ghouls/Lacedon, any creature can be aquatized fairly simply.

Make a 3D maze that they swim though (that is, a multiple levels of 2D mazes). If their capacity to go underwater is limited, make periodic air bubbles in it.

[TheThan]

For monsters there’s the aquatic template in stormwrack that will give you just about any creature you want.

I like the idea of an underwater medusa, and don’t forget the abolith. Those are great if you have to fight them in their own element.