About 80,000 of the island's annual visitors come for one thing: The area's incomparable scuba diving. With over 30 kilometers of reefs, water visibility to 200 feet, and over 200 species of tropical fish, Cozumel is considered by many as the finest dive destination in the Western Hemisphere. Water temperatures range from summer highs in the low 80's (F) to winter highs in the low 70's (F).