Read the reviews of the Akumal Beach Resort!
The best beaches to snorkel are at Akumal. Small town about 10-11 miles south of P.A. For AI resort names just type in Akumal riviera maya - click accomodations. also check out the Akumal forum. You will find lots of reef and snorkle info. from the people who love it there. Until recently, Snorkeling in front of the P A Omni hotel was great . But I just read that a stupid careless cruise ship tossed out 2 huge anchors with enormous chains and raked through the reef for over 600 feet. Guess the damage was horrible.
Playas reef is all dead. Probably caused by much the same reason. They say, Akumal reef is almost comparable to Cozumel. At Akumal, you have the great turtle nesting area. You will be able to swim with lots of turtles. Hope this works out for you.
Perfect. That was the info I was looking for.