San Lorenzo Marine Archipelago National Park, Marine national park in Baja California, Mexico.

San Lorenzo Marine Archipelago National Park protects the maritime waters around the islands of San Lorenzo, Las Animas, Salsipuedes, Rasa and Partida in the central Gulf of California, southeast of Mexicali and separated from the coast by the Salsipuedes Channel. It covers 50,442 hectares, mostly sea; the small land portion is arid, with irregular coastlines and sea cliffs, and San Lorenzo Island rises to 485 m at its southern end.

The Mexican government established this marine area as a national park in 2005 to protect its ocean biodiversity and island ecosystems. The designation reflected increasing concern for preserving this unique environment.

The archipelago lies in the municipality of Mexicali, Baja California, and is reached by boat or light aircraft from nearby towns and tourist centres. Thousands of visitors come each year, mainly to watch whales in the surrounding waters. The islands also support commercial and sport fishing in the central Gulf of California.

Visitors access the archipelago by boat from ports in Baja California, with guided tours running throughout the year. Weather conditions affect accessibility, so checking conditions beforehand helps plan the visit.

Rasa Island holds an estimated 260,000 Heermann's gulls and 200,000 elegant terns, each figure about 95% of that species' world population. The park's other islands, Salsipuedes, Las Animas and San Lorenzo, host an estimated 6,000 to 18,000 brown pelican nesting pairs.