Everyone keeps saying to leave passports locked in safe on ship...but I thought you needed to show them at ports if you got off the ship? (yes...I'm new at this...ha). Also...I know everyone is saying their belongings were safe left on a boat or in a cubby...but it makes me nervous! We are doing a Grand Cayman dolphin encounter, stingray city and the turtle farm. I'm nervous about belongings (backpack w/just-in-case pull-ups for my 3 yr old, our spending money for the day and IDs..maybe a waterproof camera. Has anyone worn this in a waterproof bag w/lanyard?