Product Description Preparation: Proper use: Full face snorkel masks are designed for leisure surface snorkeling. Serious freediving is not recommended. Strenuous swimming while wearing any type of snorkel, including full face designs, is not recommended. Be sure to take regular breaks while snorkeling. Once in the water,swim on the surface and breathe calmly through your mouth or nose,if you feel light headed remove the mask immediately,keeping your chin slightly up will create the best breathing experience,if you feel any obstruction to your breathing,it may be due to the snorkel being covered in water temporarily,the dry top snorkel design will prevent water from entering through the top of the snorkel,if water leaks into your mask,simply lift your head out of the water and it will drain out of the chin valve,no need emove your mask to clear it of water.