Wendy, Chankanaab is one of our favorite places to snorkel. There are so many fish in the snorkel area that I get a little claustrophobic. The fish aren't afraid of you and get right up in your face. Last time, we did see a barracuda but it kept it's distance.
Another time that we were there, we hit the jelly fish season and we got numerous jelly stings, which is not a good feeling!
We just take a taxi and spend the day at the beach snorkeling.