I'm not a diver, but I do like to snorkel. I have a little trouble with holding the snorkel in my mouth and breathing. This was the answer to my problem. It fits over your full face and nose. I can lay my face in the water and snorkel with the best of them now. When you dive down to pick something up, it closes off the water and you can just give a hard blow through your nose to clean the water and keep right on snorkeling.