The waterproof pouch is a good idea, I sometimes just put I.D. and a little cash in the pocket of my swim shorts, they have a Velcro type fastener, sure the cash gets wet but it still works for the odd beer or tips. We do not take passport ashore. We have never had any problems leaving cameras and bags on the bus or, if there are lockers at the water sport operator we use them. Sometimes the operator has a large “dry bag” you can use for the camera, he will take it along in the safety boat and then it is available when you stop to take pictures.