Just the cut off to the ocean. These screens are still pre alpha and a lot of night time ocean work has been done since then. In that screen I think its just the angle that makes it look like it goes to black.
Hey Tony; I'll understand if you can't comment, but can you confirm the speculation from this screencap that the AI enemies will actually react to the Leviathan, shooting at it and being distracted by it? Cos that'd be an awesome touch.