We went to Chankanaab and really enjoyed it; great snorkeling! It is spread out enough that it didn't feel crowded at all. You just catch a taxi over for about $10 per taxi, and admission to the park is $12 per person. You can rent snorkel equipment there too. It's a really nice place to spend the day. There are no pushy vendors, the grounds are beautiful, the bathrooms are clean. You can also walk on the nature trail with replica Mayan ruins (interesting, not cheesy) or play mini-golf (very small course). There are big iquanas everywhere---but don't worry, they won't bother you. There's also a bar/restaurant and, if you sit on the beach near there, they will bring food/drinks to you if you want; but will not bother you if you don't want to order. Any other questions, feel free to ask. This place was the highlight of our last cruise (family of 4, including 2 teenage boys).