Really cool glitch!
 

You have to be using a privateer ship for this.

Go into battle.

Fly off of your ship, run far away. (Find out how on youtube.com Search for how to fly pirates of the caribbean online) Wait for your ship to be destroyed, and just watch the fun!

I'm still floating exactly as far out away from my boat as I was before I was sunk, but my boat is in a new slot off of the island, so even though my boat-relative position is the same, my absolute map position is pretty different (other side of the island, actually.) Handy trick for jumping around to assassinate pirates from the enemy island.

WHOA! Third time's the charm. Just had to run all the way to the enemy island. Once boat sinks, I'm floating in "heaven" and my boat has 0 hull points...presumably invulnerable and invisible now? Nope.

OK, either I'm not doing it right, or it doesn't do invincibility. Bizarre, though.

wow you can do that simply on a regular sloop.

Gotta love people chasing a glitch when the OP didnt even tell us what it does.

"just watch the fun" is rather... well ok.. doesnt tell us anything!!!