The exterior sides of our 40L waterproof holdalls are made of nylon mesh fabric, while the interior is constructed of welded PVC for a true impenetrable seal. The trusty Fold Seal System and Velcro strip make these sailing bags 100% waterproof and suitable for quick submersion. With one external mesh pocket, two more inside and an internal wet/dry pocket too, our 60L waterproof holdalls are ideal easy-access travel, water sports, sailing or camping bag.