Make sure you go the The side with the YELLOW sign! The second side with the pink sign looks way less impressive.
Came here with the family (7 people). Took a palpa (shade cabin) for a few hours. Place is great and beautiful to relax. Water are not so clear as in other places, so the snorkeling itself isn't so recommended here (it's nice, nothing more).
Entrance fee is 14usd, you can rent gear and looker. You can't bring food and drink inside but there's a nice restaurant (quite expensive).