Overboard 30 litre ultra light pro sports backpack black waterproof pro sports backpacks have just got even better as are now available in environmentally friendly and ultra lightweight tpu fabrics with a seamless electronically welded construction and a simple to use two way sealing system making it fully submersible this waterproof backpack really should be your backpack of choice from the large front mesh zip pocket with reflective strips to the padded shoulder straps and air flow b