Bootstrap was cursed like the rest of the pirates, so he could not die.
They strapped him to a cannon and dropped him to the bottom of the sea, but he should still be 'alive' down there.
During the eight ? years he was down there, he should have been able to get free, and return to land.
Or did he suddenly drown when the curse was lifted ?
Why don't they explain this kind of thing after the credits ?
I ruined a perfectly good nights sleep thinking about it.