Snorkels have various sizes and shapes of mouthpieces (the part of the snorkel that goes in a diver's mouth). High quality mouthpieces are made of durable, soft silicon, which will not cut or press uncomfortably on the inside of a diver's mouth. Mouthpieces come in different shapes and sizes. Finding the correct mouthpiece for an individual may help reduce jaw strain. Most snorkel mouthpieces can be swapped out for different styles to maximize comfort.
Below the mouthpiece, most snorkels have a reservoir, or extended plastic bowl that drops down below the mouthpiece. Water that enters the snorkel tube will be collected in the reservoir, as opposed to traveling directly to the diver's mouth. A diver can continue to breathe with water in the reservoir until he is ready to clear the snorkel.