I'd be surprised if you find any shore diving on the Riviera Maya side. The reef is too far offshore for a swim given the currents, and I tried and failed to find even decent shore snorkeling after two weeks there. Akumal, which is supposed to be cool for snorkeling, wasn't. They will only let you dive with a dive group, so essentially you are in with tourists and wearing flotation. Also no freedive fins allowed. Basically the Riviera side for scuba is the Cenotes, which are awesome, and boat dives out to the reefs, which are just "OK" compared to Cozumel. (However there ARE some wreck dives, shark dives and of course whale sharks.) On the Cozumel side, you can shore dive. Scuba Club Cozumel, Blue Angel and other places have shore diving, but honestly other than for an extra dive, I'd go on a boat there everytime. The reefs are just too good to pass up for a mediocre shore dive, although I had fun ridding the shore of some small lionfish with my pole spear. Ok, this is all just my experience over 3 weeks last summer. If you find some decent shore diving on the Riviera side I want to know about it as well, because I'll be back there next summer!