The Catamaran Sail and Snorkel is fun for a first time cruiser or visitor to Cozumel who is nervous about being on their own. There is no sailing involved as it is basically only the shape of a catamaran with a sail that "looks nice"! The entire trip is under power. You snorkel for about 30 minutes, and then spend some time at a beach. The cost is about $60 a person through the ship. You can also book this exact same trip through Fury at the pier for about $25. (This is the same company the cruiselines use.)
There are many other beaches (Chankanaab Park, Mr. Sancho's, Paradise) where you can have a very similar experience for much cheaper. Just keep an eye on the time!