There is something about fish that makes them look happy. The big lips, the constant look of surprise, the general sense of "I'm just hanging out". I can't think of anything more peaceful than diving in 80 degree water surrounded by reef fish. Just fantastic.
And then, there are the "underwater creepy things". On dry ground snakes and spiders terrify me. Below water it's eels and urchins. This next image summarizes all I'm fearful of underwater!