Posted March 4th, 2013, 08:41 AM
I would recommend against bringing your passports. Even with a waterproof bag, you don't want to risk having them get wet!
Your bags will be locked in a bus or a van, secure but definitely something that could be broken into. In my view, the chances of having them get stolen is higher than the chance of missing the ship!
The cavetubing operators are very attentive to the time and will make sure you get back in time for the ship. Also, I've seen on the boards here that if you miss the ship, most cruise lines will empty out your safe and leave your travel docs with the port agent.