Some years ago, a friend of mine dropped my compact into the sea and all I could do was watch my poor camera sink into the embrace of Davy Jones' locker. Sometimes, that memory prompts strange thoughts of falling into the sea with a camera, and then wondering if I would have enough time to throw my point-and-shoot back onto land before it suffered a dunking with me.
When I stumbled on the Kata ABS-HD Air Bag system, I knew this was one indispensable piece of carrying gear that any adventurer/photographer ought to own. When deflated, the case is as compact as a paperback novel. But once inflated, all within a minute, it can house a professional camcorder or a dSLR and some lenses. Do note that the Kata case (which sells for about $200) is not a camera bag, but protective gear that helps cradle your equipment during transportation.
As a bonus, I reckon the ABS-HD Air Bag makes for a good float to hang onto if you're lost at sea.