I have been traveling to Cozumel for more than 10 years now. I love it there and have snorkeled Chankanaab and have taken many of the snorkeling tours the drive shops offer. Chankanaab is more of a tourist place and there are statue's and things in the water to see. But if you want the full thrill of snorkeling and see the most beautiful fish and reefs, take one of the tours and make it really worth you money. Enjoy!