Well, I'm going to have to replay it; from the second I hardly remember anything :)

I believe this is a reference to the game Bioshock 2. In that game you find out that the character Gil who was the one who created the Big Daddy Diver guys including the one you play as decide to do an experiment with Adam which turned badly for him. Which when you meet him he looks exactly like this but the tank is very murky and dark so its hard to tell.