Battered by the wind and waves, the rocky islands are mostly uninhabited except for a small military detachment and a lighthouse keeper.

Despite their barren appearance, they serve as a refuge for seabirds and support a sizable number of plants, including 6 endemic taxa found only on the islands.

Centuries later, they served as weekend getaway locations, secret gambling spots, and smuggling sites until the Mexican Navy clamped down on trespassing.

[4] The Coronado Islands are located within the central portion of the Southern California Bight, on the continental margin within Mexico's exclusive economic zone.

The islands are exposed continental blocks, produced by the shear zone of the Pacific and North American plates.

Radiocarbon dating of abalone shells within the vicinity of the ceramic artifacts suggest that site was occupied intermittently from at least 1390 to 820 calibrated years BP.

In 1602 the priest for Sebastián Vizcaíno's expedition, Father Antonio de la Ascención, called them Los Cuatro Coronados (the four crowned ones) to honor the four brothers who died for their Christian faith.

[6][4] In 1872, the Mexican Navy began visiting the islands to prevent trespassing and reduce the damage from human impact, although business ventures still proceeded regardless.

Colonel Manuel Ferrer and Tore Fidel Pujal, the editor of the newspaper La Baja California, secured the North Island in 1873, planning to use the stone.

[4] In the 1920s and 1930s, during prohibition, the cove on the northeast side of South Coronado Island was used as a meeting place for alcohol smugglers.

Since it was the time before radar, and as foggy nights are common on the islands, the large number of boats frequently resulted in collisions.

There was so much traffic that a famous casino, an elaborately constructed two-story building known as the Coronado Islands Yacht Club, flourished well into the Depression.

The casino was forced to change trajectory after the Mexican government made gambling illegal only eighteen months after it opened, re-opening the next year as a weekend getaway hotel.

These were suspended for some time, before briefly starting back again in 1958, with the steamer Silver Gate towing a glass bottom boat to the cove on South Coronado.

[6] In May 1943 the U.S. Navy's USS PC-815, commanded by L. Ron Hubbard, the future founder of Scientology, conducted unauthorized gunnery exercises involving the shelling of the Coronado Islands, in the belief they were uninhabited and belonged to the United States.

It forms a transitional zone between the Mediterranean ecosystems of the California Floristic Province and the subtropical deserts of western North America.

[17][18] Anacardiaceae Apiaceae Asteraceae Boraginaceae Brassicaceae Cactaceae Caryophyllaceae Chenopodiaceae Cleomaceae Convolvulaceae Crassulaceae Cucurbitaceae Euphorbiaceae Fabaceae Hydrophyllaceae Liliaceae Malvaceae Montiaceae Nyctaginaceae Orchidaceae Papaveraceae Plantaginaceae Poaceae Polemoniaceae Polygonaceae Polypodiaceae Pteridaceae Ranunculaceae Resedaceae Rhamnaceae Rosaceae Rubiaceae Sapindaceae Saxifragaceae Solanaceae Themidaceae Urticaceae Zosteraceae There are colonies of birds that nest on the islands and can be spotted in the nearby waters like gulls, cormorants, pelicans, storm-petrels, and alcids.

[19] Pilón de Azúcar, better known as Middle Rock, is host to the northernmost nesting colony of brown boobies on the west coast of North America.