If it's done on SqtgDog's server; I as the Demi-God will be glad to give a little extra help. :p I won't just spawn all the blocks and throw god on to build underwater but I have some ideas. I could get it started and then help enchant some helmets for longer breathing underwater and improved breaking speed underwater and I'll be glad to hand out some enchanted tools/books. Don't forget we have the power to use /back and /home too.
I wish we could wait for the update so we could make it using NetherQuartz blocks:
IF YOU GUYS ARE SERIOUS ABOUT THIS; I think we could do it.
We should start by building a group outpost to begin at, and we can all begin gathering supplies nearby on land; and we could have a warp set in the ocean/lake we'll be working on. I imagine we'll be building this on the ocean floor and expanding it from there, so we'll need LOTS of sand for glass, tons of coal for all the smelting, stone and wood for crafting, a decent amount of iron and so on. Redstone, obsidian, glowstone, netherbrick, and netherquartz once it's here.
We have a lot of work to do so everyone can start collecting supplies now to prepare and we can all pool them into a community chest when we're ready.
I'll start flying around the world and marking interesting spots to build Atlantis.