When I was in Cozumel I did a sailboat to a snorkeling reef. The 1st stop we did we were in about 15 to 20' of water. The 2nd stop which was actually near the 1st place but just deeper. It was around 30 - 35' of water. There were some large fish that would swim around us cause the guide was feeding them. The smaller colorful fish like butterflys & queen angel fish stayed way at the bottom. I would love to go back but this time snorel in about 5 - 8' of water. Is there good snorkeling in that depth around the island.