I bought one of those snorkeling vests for my then 5 year old, and they are much easier to deal with than a life vest, because they deflate and inflate as much or as little as you need. Remember, the salt water is very bouyant (sp?). And they are actually comfortable. All the snorkeling excursions I have ever been on have them. It's just easier to have one that has been fitted ahead of time for the little ones. I think I got it at Diver's Direct via the Internet, but a little surfing via Goggle or another should land you in the correct place. Also, you may want to invest in a good pair of goggles, as opposed to the full face mask. Less cumbersome, and if the child is not a good swimmer, they are not going to breathe thru the snorkel anyway. And you won't have to fit it every time. Have fun.