This mountainous island, Mexico's largest, lies 3km off the coast from Punta Chueca. It was once a Seri homeland, but was depopulated when the island was declared a nature reserve in 1963. Today it's administered by the Seri tribal authorities. An intact desert ecosystem, it's home to bighorn sheep and large colonies of seabirds. There's good snorkeling around its coast. For a permit and guide to the island, ask at the Consejo de Ancianos at the entrance to Punta Chueca.
Recommended guides include Ernesto Molina, Alejandro Barnet and Genaro Robles who can set up tours (per boat M$1200).