Cozumel has some good shore snorkeling too. We stayed at the Coral Princess (north of town) and right off their dock is some awesome stuff. Excellent vis and lots of rays, tropicals, and eels. We snorkeled for hours up and down the shoreline. There can be quite a bit of a current, so pay attention and ask the dive shop on premises they can tell you which way the current usually goes and where to get in/out at. have fun. I'm jealous.