Can i exit with a treasure any open door thatbgoes outside the ship? Or is there the starting tile and one other designated tile only
Those other doors just go to rooms you haven't flipped over yet. Or possibly directly into the ocean where your boat isn't parked and the sharks are ready for bbqed pirate.
As such, the only allowed exits are the one single door on the main entrance tile and the dinghy that you might get to place when you flip over the very last tile.