I've tried the mylar balloon myself with varying degrees of success.The quality between brands varies,but eventually they all seem to tear.I went with some of the larger,high quality ziplock bags for water carry backup,with more to segregate items in my larger kit. The large intestine of potential food animals makes a fine water container.As an aside,mylar and aluminum are very deadly to wildlife should they be abandoned.I know of two pelicans and a sea turtle that died from ingesting mylar balloons.The taste of uluminum is very sweet to many mammals.Once ingested,it irritates the stomach lining into swelling.The animal starves to death.<br><br>