Ok, I've looked over the characters. We have:
A Human Hexblade
A Triton Paladin
A Sea Elf Monk
A Triton Druid
A Water Genasi Fighter
A Halfling Rogue using the Robe of the Manta Ray
So only two who aren't native to the waters, and one of those is a Warlock with an invocation. This is a great party. Very eclectic. I love it. two front liners, two skirmishers, a blaster and a druid.
I can now start working on this a little each night. I do not expect posting to be fast, but when I have something to post I'll try to at least post once an evening. Part of the speed of PBP is the speed of the players. Here are some ground rules I'll be using. Not underwater specific, just ground rules.
Set initiative, which means your initiative is 10+Dex+Bonus (If any). I'll calculate all that out later. This way, there's no rolling, fast people are always fast and slow people are always behind the ball. However, Initiative really only matters in the first round. The bad guys will all be on their own initiative, so once they go, it becomes Block Initiative, with first come first serve rules.
Please Please Please be creative. I am giving you all freedom to create what you will, story wise. Add little details to the scene, if you want to. Leave bad guys and such to me, as well as any items that could be useful, but if you want to say the door is covered in brightly colored barnacles, please do so. If I mention a city, and you think you've been there and it makes sense that you've been there, say so, or say something here and I'll either veto or give you the thumbs up. I'm going to be very flexible with story elements, so please add in what you like. Obviously be reasonable, and only put in observations, not actions of others around you, but have fun with it and be creative.
Well, that's all. I'll put some work in this week and have the IC up as soon as I can. I'm hoping this will be relatively quick, and if we all have fun it can be extended.