i shoot everything with a minolta srt101, so if the body gets ruined its a $90 replacement... no electrics on this camera. no automatic exposeure or anything like that, its a 1970's camera... i carry two camera bodies in the field, along with another backup in the luggage....
i used a medium sized waterproof bag to put the camera and lenses in when paddling in the tubes. when walking in the caves i pulled the camera out and carried it.
used a 20mm lens mostly, and a flash that is solid to 70 feet. focused by estimated distance. i used the headlamp to try to frame the pic a little. pretty tough to frame facing black. i'd try to wave the headlamp around a bit while looking thru the viewfinder to try to get some idea of the edge of the frame.
used 200 ASA film...
there is a constant drip from the cave ceiling, not like heavy rain or anything, but a camera dependent on electrics might have more trouble. its interesting carrying the camera in one hand, the bag in the other. no hands left to scramble with when hiking in the caves, so keep the body low and well balanced!!!!
i do however, highly recommend this activity!!!!!
my dad is 70, and we were a tad worried, but he kicked ass and loved it, and they had a guide, Vita, who watched him closely, and pa really appreciated that. always had an arm to lean on if necessary... or help chasing that tube when it gets away!!!!!
what a gas though. everyone just loves the cave tubing/hiking. the black hole drop (hundred(s)? of feet down rapelling into caves) is another favorite... especially in a monsoon!!!! its amazing how the caves branch guides can take rookie scaredy cats and get them safely and proudly down that rope... certainly gives one confidence to face their fears.
my wife just about killed me when she realized she and her babies (then 18 and 21) were going off that cliff and down that rope. but everyone did superbly due to the great guide skills of the guides of caves branch... (carlos, abel, walter, vita, pedro- we thank you all)