An afternoon spent at your local swimming hole is great. Changing out of your suit and carrying a soaking wet bag home, not so much. The solution: put your damp swim trunks in this, and the rest of your pack will stay dry as a bone. If you're headed out onto the water, toss your phone and wallet inside to keep them safe from the occasional splash. If you're headed from the weight room straight to the office for a day of work, use it to stash your sweaty gym clothes. And when it's not in service, the bag folds up into a small silicone droplet that easily attaches to your keys or zipper pull.