Cozumel is a Caribbean island just off the Yucatán Peninsula in southeastern Mexico. It has great diving, nice people, safe streets, and prices comparable to other Mexican tourist destinations. The diving is the main draw to Cozumel; if you prefer white sandy beaches then other nearby destinations would be a better bet (e.g., Playa del Carmen, Tulum, Isla Mujeres.) It was badly battered in 2005 by Hurricane Wilma, but, with few exceptions, has been completely repaired.
Most visitors travel to Cozumel to dive and see its wonderful underwater life. While there are quite a few beach clubs that offer snorkeling, the main attractions are the reefs offshore and the multiple dive shops and operations are always ready to take you there.
The main town, San Miguel, and dive operations are on the west side of the island, but if you rent a car or scooter then the east side of the island is the place to go. The east side of the island is mostly undeveloped, but there are beautiful beaches, big waves, and rocky outcrops over the ocean.