In an effort to drink more water, many of us carry a reusable water bottle everywhere we go. Once empty, a clunky water bottle can be a bit of a drag. Here is an ingenious solution. The Hydrapak Stash is a water bottle with a rigid top and bottom that gives it structure to stand on its own. Once empty, the soft side slips into the top and bottom as they twist to lock together, making a small disk you can just toss in your bag or jacket pocket and forget. It holds 25 ounces and is dishwasher safe. Bonus.