On the East coast of the Yucatan, I stayed at some cabanas near Tulum (there are dozens of places) that are right on the beach. I don't know the snorkeling situation - but they were really relaxing. It doesn't seem like it when on the beach - but there are a lot of different cabana owners so I'm sure there's one to fit any need.

Marguerite in Chicagoland http://www.mtczajka.net