lol, same here, I thought you were supposed to jump over as well. I got bored and ended up trying to drown myself, that's when I noticed the underwater tunnel. :)
[spoiler:e7850b90a0]
There's a tunnel under the water. Swim into it an open the door to get into the bow. Once you are inside, swim left and open the only door you can see. After getting the door swim as fast as you can (straight) and you'll surface just in time before you drown.
also -...