Question: How does Will get out of the sinking Interceptor? He is stuck there, it's full of water. Several minutes later (it must be some time later, because the Black Pearl had time to move away) the ship explodes, and Will shows up. How did he do that?
nightline
Answer: The explosion damaged the ship enough for him to get out.
Chosen answer: Heavy objects are easier to lift when submerged in water. It is quite possible that once submerged, he was able to lift a hatch that he was not able to do before.
Scrappy