Assuming the boat was sinking, then its because they jumped off the boat, considering it’s the logical thing to do in a ship wreck, so that you don’t get stuck on/inside the ship, and because of cavitation. When the ship breaks the surface of the water it pulls air down and aerates the water around it. Aerated water does not have the mass of non-aerated water, and the ship can’t push against it effectively to float, so it sinks faster, and it pulls anything nearby down with it. Because of this your unable to swim in the water and drown with the ship and anything inside it.
Hope this helps!
The first sentence is the answer
Antagonist. The protagonist is usually the "bad" guy or the person who usually causes the problems for the antagonist.
