We spent the day at Cozumel on a snorkeling cruise. It was fun, but very short. They just wanted to get you in and out so they could dump you off and pick up another load of people. I know others (including boat staff) who save their money and snorkel at a small beach area just a few yards north of the dock where the cruise ship docks. I would recommend a couple hours of snorkeling at the dock and then maybe a cab ride into town. THE SNORKELING CANNOT BE MISSED!!