Some of the basic mask features are the skirt, mask strap, and purge valve. The mask’s skirt is the area which seals around a diver’s face and keeps water out. A mask strap and adjustment buckles allow the diver to tighten or loosen the mask until it properly fits around the head for optimal comfort as well as a secure mask. A popular feature on certain masks is the addition of a purge valve, located on the bottom of the nose section, to help in clearing the mask of water more easily. All of these popular features are added to make your next snorkeling adventure as comfortable and enjoyable as possible!