Sharpknux was the man behind this start on a map - the fact that there is no light on my pistol is usually a bit of a clue that he was the maker! I don't know if he intends to continue with this map, of which only a broad outline has been made, really. A big upper lake; dive into it, swim through one of the passages in the dam, and dive out into the lower lake. Over to the right at the bottom, a tiny speck is actually an elevator that will take you bacxk up again.
So, it is an idea, but it will take rather more than that to turn this into a finished map...