I purchased this for a small trip to Hawaii last summer, and it was the perfect travel companion. Small, comfortable, light-weight, and it holds EVERYTHING. I used it as my carry on item for my flight, and my pack for our day hikes. Holds a full size beach towel, extra shirt, sunscreen, portable iPod stereo, box of granola bars, and a few cans of beer :-) Not to mention the hydro-reservoir. In addition, it has the clip on the front of the shoulder straps to keep it nice and tight to your chest so it doesn't slosh around while you wear it, as well as hold the bite valve in perfect reach of your mouth, so you don't have to hold onto it with your hands each time. Water stayed cold ALL day long.