Sixteenth to nineteenth century and the rest of the Revillagigedo Archipelago, and extent of Mexico's western
EEZ in the Pacific No evidence of human habitation on any of the islands exists before their discovery by Spanish explorers.
Hernando de Grijalva and his crew discovered an uninhabited island on 19 December 1533, and named it
Santo Tomás (
Socorro Island) and on 28 December they discovered
Isla de los Inocentes (
San Benedicto) which owed its name to having been found on the day of the
Holy Innocents. In November 1542,
Ruy López de Villalobos, while exploring new routes across the Pacific, rediscovered
Inocentes and
Santo Tomás and charted the latter as
Anublada ("Cloudy"). Villalobos was the first to report sighting of
Roca Partida Island giving it its present-day name. In 1608, Martín Yánez de Armida, in charge of another expedition, visited
Anublada and changed its name to
Socorro. In 1779 José Camacho was the first to report sighting of the island remaining, that he charted as
Santa Rosa ("Saint Rose").
Santa Rosa was later renamed
Clarion after the vessel commanded by Henry Gyzelaar at that time. The Revillagigedo Islands have been visited by a number of other explorers:
Domingo del Castillo (1541),
Miguel Pinto (1772),
Alexander von Humboldt (1811),
Benjamin Morrell (1825), Sir
Edward Belcher (1839) who made the first botanical collections and Reeve, who witnessed the eruption of Mount Evermann in 1848. On 25 July 1861,
President Benito Juárez signed a decree awarding territorial control over the four islands to the state of
Colima. His plan was to build an offshore penitentiary on Isla Socorro; although this never happened, the decree whereby they were attached to Colima has never been repealed. In 1865, the island was explored by ornithologist
Andrew Jackson Grayson, who discovered the
Socorro dove,
Socorro mockingbird and the Socorro
elf owl which were later given
scientific names in his honor.
Twentieth century At the beginning of the twentieth century, Dr.
Barton Warren Evermann, director of the
California Academy of Sciences in
San Francisco, California, promoted the scientific exploration of the islands. The most comprehensive biological collections were obtained at this time. The volcano on Isla Socorro was renamed in his honor. In 1957 the Mexican Navy established a naval base on Socorro and has had a permanent presence on the island since then. A tiny outpost also exists on Clarión, as noted above. On 21 March 1972, became the first
Governor of Colima to visit his state's island territories. A plaque was unveiled to mark the event and cement Colima's claim. The seas surrounding the larger islands are popular with
scuba divers; a variety of marine life such as
cetaceans,
sharks and
manta rays can be observed. Visitors usually stay aboard expedition vessels during their visit to the islands, which is desirable from an ecological standpoint to prevent introduction of further
invasive species. The islands are considered dangerous to visit for purposes beyond diving since it is difficult to make a landing; some have nearly lost their lives attempting to do so on Clarion for example. They are occasionally visited by
amateur radio operators, who usually use the
ITU prefix XF4. Because of their distance from the mainland, for award credit they are considered to be an "entity" separate from Mexico. Expeditions from organizations engaged in
biological conservation of the islands visit the islands for fieldwork on a regular basis. No
tourism facilities exist; the islands have no reliable sources of fresh water of their own. ==Ecology==