Deep Surface

Deep Surface is the monstrous progeny of a strange romance between a reading machine and a free-diving simulator. Literature at crush depth. Hypertext gets wet. Generically, it is yet another instrument: one of those things you can play (or play with), without playing a game. There are rules here, and procedures, and (as in Real Life) a more or less invisible scoring system; so astute players may be able to invent clever and even elegant strategies. But if you're not feeling astute, you can plunge in and have a dip, immersing yourself in what signs and symptoms may present themselves as you pass by, dreaming perhaps of meaning... till robot voices wake you, and you drown.

(Source: Author's description from Electronic Literature Collection, Volume Two)