I've run two games with this premise. The first was many years ago, back before underwater archologies were actually introduced in the cannon. I had to come up with rules for subs, dive suits, equipment, all kinds of stuff. My players loved it, tho. More recently, I was running a PbP game here on the boards (
Into /
IC) using an updated version of the same plot, but that game seems to have died before the players actually made it to the archology.
At any rate, I have a lot of ideas (including background and NPCs) and a set of maps I've been working on that I might finish someday (here is a
preview- a geo-thermal power plant separate from the larger archology). I'd be happy to share, if your interested. I could post things here in spoiler tags or share by PM (not that there's much hope for my game, but whatever...)