Underwater World

[Mindartis]

So, Im starting a new campaign sometime soon, and I had a cool idea. Why not create a brand new Underwater world? Right now, the concept of the world is that a major something drove them to the waters, and they hid there for millenia, adapting, evolving, to suit life under the water. Animals they brought with them (Experiments, Zoo's, etc) Also managed to evolve. Dragons have become more serpant like, Owlbears wings are now like Manta Rays, yada yada yada. What Im more concerned about is the rules. Im homebrewing this, and therefore messing with the system a bit. RIght now, my rules are...

•Elementals are out, exception of water ones.
• Includes Genasi, exception again of water ones.
•Bows are out. Crossbows are like Mini-harpoon guns
•Most spells involve Force and Water damage. Ones dealing with fire are non-existant, and lightning is frowned upon.
• Most animals have adapted to water-surroundings. Thousands of years of evolution and whatnot.
• Few gods remain. Those still around are basically water gods or things that are still applicable.
• Version of the Underdark, called the Abyss (original, right?)
• Warforged are out
• Fire damage is out all-together. Whether it be Dragonborns breath, Teifling abilitys, doesnt matter.
• Demons are now water based.
Druids are now essentially Aquaman.
Rangers pretty much non-existant
Weapons were modified to be really fast and deadly underwater.

Of course, these rules don't apply above water. Im going to have the party be the first people to vnture out from their underwater safehouses, encountering normal people and civilization.

What suggestions do you guys have? Anything would be greatly appreciated.

[B!shop]

You can justify the underwater migration with a nearly mythical cataclysm that destroyed life on the surface, forcing the survivors to settle under the seas in a past age.

Perhaps a great magical fire started, burning everything on the suface, and the oxygen began to run out.
Legends say that the fire is inextinguishable , and this is why the survivors (today the inhabitants of the underwater world) never come back to the surface.

[hamishspence]

What's wrong with the idea of magma paraelementals, ooze paraelementals, etc on the sea floor?

[megahobbit]

If travel underwater is possible humans would need away to keep them neutrally bouyant like weights.

[Zigg]

Maybe Sea Serpents could replace Dragons and have a Water Damage Breath. And then Serpentborn could replace Dragonborn?

Maybe instead of Windwalk there could be some kind of Jetski like movement. Waterush?

[Aeolius]

You might find this thread (http://www.giantitp.com/forums/showthread.php?t=158481&highlight=undersea) useful.

As far as current undersea supplements go, you might also want to take a look at Cerulean Seas (http://www.alluriapublishing.com/cerulean1.htm)