The first people to settle in the area which is now known as Cozumel, Mexico were the ancient Mayans.  Today, the Maya ruins are popular tourist attractions. 

The top Mayan ruin site on the island that's easily accessible by scooter, car, taxi, etc., is San Gervasio, located almost in the middle of the island.  It's a 20 minute drive from downtown San Miguel, and you don't need a guide to take you there, just a decent map of the island.  There are also some small Mayan ruins and caves at El Cedral which is in the southern interior.  An extremely fun way to see them is to sign up for a 2 hr. ATV tour that is located right near the ruins.  It's more fun than history, but it's still quite interesting and you get to see a cenote (sinkhole) too.  There are several ruins located along the northeast coast of the island, but you cannot access these unless you are with a designated guide and/or group.  Private vehicles and taxis are not allowed on the road. 

Sadly, with the influx of Spanish conquistadores and the resulting small pox plagues which affected the area, most of the Mayans were eliminated from the island before the end of the seventeenth century.  Two hundred years later, Cozumel was re-settled by the Mexicans. 

Cozumel remained a little-known place until it an uderwater movie was made here in 1956 (and later shown on U.S. TV in 1957) by Mexican movie director Rene Cardona.  Soon, tourists began to arrive seeking the clear waters shown in the film, and before long, the tourism industry took off.  In the late 1970s, a deepwater pier was built south of town to facilitate the arrival of large cruise ships.  Since then, Cozumel has become the number one cruise ship destination in the world.