Nothing more than a dark shadow against the moonlit surface of the water. The lights were not much, though, and seeing the ship wasn't that easy.
With a last burst of speed, they broke through the waves, their massive bodies launching into the air like torpedoes shot from a submarine. It was just that their bodies were almost as big as a submarine.
Erik and the others saw the two as they arced over the ship. Water cascaded off their bodies as they soared through the air.
It would have been a breath-taking sight for everyone there, and not one of the good type. It was also beautiful.
In a way, it was, but of course, the people seeing it would have witnessed two gigantic monsters jumping over the ship they were on.