Directly offshore from San Bruno is a small island of San Marcos, known for abundant gypsum deposits and proximity to prime yellowtail fishing. Like Santa Rosalía, this is a company-built town.

About 700 people live and work for the mining company, which has been in business since 1923 and for many years has been the top producer of gypsum in North America. The town’s gypsum-block church was built in 1954.

There are no hotels and limited supplies on the island, available from one general store and a few tiendas. The island also has cell phone service and Internet.

Diving and Snorkeling

Head to Punta Piedra Blanca at the northwest end of the island for the best diving and snorkeling. On the east side, Punta Gorda and Punta La Chiva are also good sites to explore.

Mulegé-based Cortez Explorers (www.cortez-explorers.com) runs boat trips to Isla San Marcos for US$110–135. Michael Hans Kanzler, a.k.a. Isla San Marcos Mike (cell tel. 415/244-8451, www.islasanmarcos.com) has run sportfishing charters on the island for nearly 20 years. Rates are US$225 for trips around Isla San Marcos and US$275 for trips to nearby Isla Tortugas.

Prices cover up to three people for a half day, starting at dawn and ending in the early afternoon. Rates are US$25 less for dive charters to the same destinations.

Getting to Isla San Marcos

The best way to get to Isla San Marcos is to hire a panguero at the harbor in San Bruno.