My husband found out the hard way. When snorkling and you have a mustache use vasoline to seal the mask to your face. My husband almost drowned.... No one told us until our boat trip back to land. He told the crew, "thanks, I could have used that information WHILE I was snorkling since now it won't do me any good". LOL We laugh about it now, but then he wasn't. Gotta go....Cruise on!!!!!