I've never had a problem with submerged object per se, my fears ae generally confined to squishy, slimy, stingy, marine lifeforms like jellyfish and mollusks.
One thing that endlessly fascinates me and gives me chills, though, is watching a ship break apart and slide into the bottomless depths in GWX. There's definetly something interesting about the frigid, lightless, deep.
edit-btw, I love the screen name.