REI Balance Gym Bag
I can't get enough of REI's bags made from recycled plastic bottles. They looks great and are so incredibly practical - I couldn't have designed them better myself! They don't miss a beat with their gym bag: it has a big side pocket that holds a 1L water bottle, a separate compartment for your dirty gym clothes with an airy mesh ventilation system that keeps your clean clothes looking and smelling fresh, and get this: a removable shower caddy for you to keep your toiletries in that easily transports from your bag into the shower. Genius, I tell you. Plus, it has straps for your yoga mat on the side of the mat, unlike some bags where it straps on to the underneath so you can't set your bag down. And of course, the essential zippered pocket for keys, wallets, cell phone, etc. Can you think of anything they left out? Cus I surely can't. Comes in black and blue.
In my quest of finding a more compact, but diverse gym bag ~ this one MAY be the winner. It separates dirtly clothes from clean and shoes ~ my main concerns. Plus it will fit in the narrow locker. Bonus: Recycled polyester (plastic bottles)