I was thinking that it would be a simple idea for the camelback manufacturers to make a bladder that can fit into a BC pocket. You could probably get a litre or so of water in there and use the existing drink tube to get a drink of water underwater! As there is no air in the bladder, I don't think it will be affected by pressure? Also, full face masks and commercial dive helmets could be manufactured with a drink tube like the military NBC masks with an adapter. Could you let me know how to submit this idea to Camelback?