You can hire a tour guide to take you out on the waters of the lagoon where you can see the dolphins. Tours usually go out to Isla Pajaro (Bird Island) which is where thousands of aquatic birds nest. The tours cost about M$500.
Faro Museo
Two-story lightkeeper's house topped by an 18-meter high tower built in the 19th century to provide a beacon to sailors approaching the island. The museum comprises three galleries, one of which explains INAH's underwater archaeological explorations. Outside is a habitat for iguanas and turtles.
Beautiful uncrowded beach. Wide white sandy stretch scattered with seashells. Bring what you need because there are no food or drink vendors on the beach.
Uncrowded but populated beach with a few vendors and cabanas for rent. Calm waters good for swimming.