The Gulf of California ( es, Golfo de California), also known as the Sea of Cortés (''Mar de Cortés'') or less commonly as the Vermilion Sea (''Mar Bermejo''), is a marginal sea of the
Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south and is bounded by the continents of Asia ...

Pacific Ocean
that separates the Baja California Peninsula from the Mexican mainland. It is bordered by the states of Baja California,
Baja California Sur Baja California Sur (; en, "South Lower California"), officially the Free and Sovereign State of Baja California Sur ( es, Estado Libre y Soberano de Baja California Sur), is the second-smallest Mexican state by population and the 31st admitted ...

Baja California Sur
Sonora Sonora (), officially Free and Sovereign State of Sonora ( es, Estado Libre y Soberano de Sonora), is one of 32 states which comprise the Federal Entities of Mexico Mexico ( es, México ; Nahuan languages: ), officially the United Mexican ...
, and Sinaloa with a coastline of approximately . Rivers which flow into the Gulf of California include the
Colorado Colorado (, other variants) is a U.S. state, state in the Mountain states, Mountain West region of the United States. It encompasses most of the Southern Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the weste ...

, Fuerte, Mayo, Sinaloa,
Sonora Sonora (), officially Free and Sovereign State of Sonora ( es, Estado Libre y Soberano de Sonora), is one of 32 states which comprise the Federal Entities of Mexico Mexico ( es, México ; Nahuan languages: ), officially the United Mexican ...
, and the
Yaqui The Yaqui, Hiaki, or Yoeme, are a Uto-Aztecan-speaking indigenous people of Mexico in the valley of the Río Yaqui in the Mexican state of Sonora Sonora (), officially Free and Sovereign State of Sonora ( es, Estado Libre y Soberano de Sonor ...

. The surface of the gulf is about . Maximum depths exceed because of the complex geology, linked to
plate tectonics File:Earth cutaway schematic-en.svg, upright=1.35, Diagram of the internal layering of Earth showing the lithosphere above the asthenosphere (not to scale) Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτον ...
. The gulf is thought to be one of the most diverse seas on Earth and is home to more than 5,000 species of micro-invertebrates. Parts of the Gulf of California are a
UNESCO The United Nations Educational, Scientific and Cultural Organization (UNESCO french: Organisation des Nations unies pour l'éducation, la science et la culture) is a specialised agency of the United Nations The United Nations (UN) is an ...

World Heritage Site A World Heritage Site is a landmark or area with legal protection by an international convention administered by the United Nations Educational, Scientific and Cultural Organization (UNESCO). World Heritage Sites are designated by UNESCO for ha ...



International Hydrographic Organization The International Hydrographic Organization (IHO) is an intergovernmental organization An intergovernmental organization (IGO) or international organization is an organization composed primarily of sovereign states (referred to as ''member sta ...
defines the southern limit of the gulf as: "A line joining Piaxtla Point (latitude 23°38'N) on the west coast of the mainland of Mexico, and the southern extreme of Lower California". The gulf is long and wide, with an area of , a mean depth of , and a volume of . The Gulf of California includes three faunal regions: # the Northern Gulf # the Central Gulf # the Southern Gulf One recognized transition zone is termed the Southwestern Baja California Peninsula. Transition zones exist between faunal regions, and they usually vary for each individual species. (Faunal regions are distinguishable based on the specific types of animals found there.)


Geologic evidence is widely interpreted by geologists as indicating the gulf came into being around 5.3 million years ago as plate tectonics, tectonic forces rifted the Baja California Peninsula off the North American Plate. As part of this process, the East Pacific Rise propagated up the middle of the Gulf along the seabed. This extension of the East Pacific Rise is often referred to as the Gulf of California Rift Zone. The Gulf would extend as far as Indio, California, except for the tremendous river delta, delta created by the Colorado River. This delta blocks the sea from flooding the Mexicali and Imperial Valleys. Volcanism dominates the East Pacific Rise. The island of Tortuga Island, Baja California Sur, Isla Tortuga is one example of this ongoing volcanic activity. Furthermore, hydrothermal vents due to extension tectonic regime, related to the opening of the gulf, are found in the Bahía de Concepción, Baja California Sur.


The gulf contains 37 major islands – the two largest being Isla Ángel de la Guarda and Tiburón Island, Isla Tiburón. Most of the islands are found on the west side of the gulf. In fact, many of the islands of the gulf are the result of volcanic eruptions that occurred during the early history of Baja California. The islands of Islas Marías, Islas San Francisco, and Isla Partida are thought to be the result of such eruptions. The formations of the islands, however, are not dependent on each other. They were each formed as a result of an individual structural occurrence. Several islands, including Isla Coronados, are home to volcanoes. The gulf has more than 900 islets and islands which together total about 420 hectares. All of them as a whole were enacted as "Area Reserve and Migratory Bird Refuge and Wildlife" on August 2, 1978. In June 2000, the islands were designated a Mexican Flora and Fauna Protection Areas, flora and fauna protection area. In addition to this effort by the Mexican government, for its importance and recognition worldwide, all islands in the gulf are also part of the international program "Man and Biosphere" (MAB) and are part of the World Reserve Network UNESCO Biosphere as Special Biosphere Reserve. Because of the vast expanse covered by this federal protected area, conservation and management is carried out through a system of four regional directorates (one per bordering the Gulf of California state). The work of direct and indirect conservation done in the islands is governed by a single management program, published in 2000, which is complemented by local and specific management programs. The Directorate of Protection Area Wildlife California Gulf Islands in Baja California is responsible for 56 islands located off the coast of the state. These are grouped into four archipelagos: San Luis Gonzaga or Enchanted, Guardian Angel, Bahia de los Angeles and San Lorenzo.

Shores and tides

The three general types of shores found in the gulf include rocky shore, sandy beach, and tidal flat. Some of the rich biodiversity and high endemism that characterize the gulf and make it such a hotspot for fishing can be attributed to seemingly insignificant factors, such as the types of rocks that make up a shore. Beaches with softer, more porous rocks (such as coquina limestone, rhyolites, granite, or diorite) generally have a higher species richness than those with harder, smoother rocks (such as basalt or diabase). Porous rocks will naturally have more cracks and crevices in them, making them ideal living spaces for many animals. The rocks themselves, however, generally need to be stable on the shore for a habitat to be stable. Additionally, the color of the rocks can affect the organisms living on a shore. For example, darker rocks will be significantly warmer than lighter ones, and can deter animals that do not have a high tolerance for heat. The northern gulf experiences tidal ranges of up to . Mixed semidiurnal tides are the norm throughout most of the Gulf.


There are a number of negative estuary, estuaries, that is, ones in which the evaporation of seawater is relatively greater than that of the fresh water input. The salinities of these inlets are higher than that of the ocean. The temperatures, Poikilotherm#Ecological niches, poikilothermal, of these negative estuaries also are higher than the general temperature of the gulf. It is possible that at one time these estuaries were positive, that is, ones in which the seawater component is diluted; therefore, the water is brackish water, brackish, with salinity less than that of the ocean. However, because of human settlement around the gulf and water diversion for municipal and agricultural use in an area of comparatively low rainfall, there are no longer many rivers that freely empty into the gulf. The upper Colorado River Delta is one example of a historically major estuary and wetlands ecosystem, that since the 20th century construction of upriver dams and diversion aqueducts on the Colorado River, is now a small Ephemerality, ephemeral remnant estuary. The remaining gulf inlets still are important to several species of fishes, crustaceans, and shellfish that are commercially harvested.



Even though the shores of the gulf are generally sheltered from the continuous wave shock that is experienced by most other North American shores, storms known as a "chubasco" can cause significant damage to shorelines, despite their brevity.


The depth of the water helps to determine its temperature. For example, shallow depths are directly influenced by the local temperature of the air, while deeper waters are less susceptible to changes in air temperature. The temperature of the water in the gulf generally experiences lows of in winter and highs of in summer. But temperatures can vary greatly in the gulf, and the water is almost always warmer by the coast than the open ocean. For example, the waters surrounding La Paz reach in August, while the waters in neighboring city Cabo San Lucas, only reach .
Occasionally, the northern gulf will go through significantly cold winters. The water in the northern gulf can sometimes drop below , which can lead to a large die-off of marine organisms. The animals most susceptible to the large decrease in water temperature include macroscopic algae and plankton.

Marine life

The narrow sea is home to a rich ecosystem. In addition to a wide range of Endemism, endemic creatures, such as the critically endangered vaquita, it hosts many migratory species, such as the humpback whale, Gray whale, California gray whale, killer whale, manta ray, Humboldt squid and leatherback sea turtle, and the world's largest animal, the blue whale. The unusual resident populations of fin whales and sperm whales do not migrate annually. The area near the Colorado River Delta has a small remnant population of totoaba. This region has historically been a magnet for world-class Recreational fishing, sport fishing activities, with a rich history of sporting world records. The region also has a rich history as a commercial fishery. However, the data vary wildly according to the species being studied, and the gulf's ability to recuperate after years of overfishing remains uncertain. Moreover, changes in terrestrial ecology, such as the vast reduction in flow from the Colorado River into the gulf, have negatively affected fisheries, particularly in the northern region. The gulf sustains a large number of marine mammals, many of which are rare and endangered. Its more than 900 islands are important nesting sites for thousands of seabirds, and its waters are primary breeding, feeding, and nursing grounds for myriad migratory and resident fish species. For decades, the gulf has been a primary source of two of Mexico's leading marine resources, sardines and anchovies. Water pollution is a problem in the gulf, but the more immediate concerns are overfishing and bottom trawling, which destroys eelgrass beds and shellfish. Efforts by the Mexican government to create Nature conservation, conservation zones and nature reserves have been hampered by lack of enforcement resources as well as a lack of a political consensus on this issue of conservation of the Gulf. This occurs even though significant areas are a UNESCO World Heritage Site. The thousands of miles of coastline are remote and difficult to police, and the politically powerful commercial fishing industry has been slow to embrace even economically viable conservation measures. Conservation of the gulf's fisheries and coastlines is also complicated by a long history of overcapitalization in the sector, and the direct, often negative, impacts that conservation measures have on the livelihoods of Mexico's coastal inhabitants. At present, the Mexican government and business interests have promoted a macro-level, tourist development vision for the gulf, the impacts of which on local ecology and society are uncertain. In 2019, the gulf was added to the List of World Heritage in Danger because of concerns of the imminent extinction of the vaquita, an endemic porpoise in the area. Coastal communities are highly reliant on both commercial and sport fishing, including San Felipe, Baja California, San Felipe, San Carlos Nuevo Guaymas, San Carlos, Cabo San Lucas, La Paz, Baja California Sur, La Paz, Loreto, Baja California Sur, Loreto, Guaymas, Bahía Kino, Puerto Peñasco, Topolobampo and Mulegé. The well-developed shrimp and sardine fleets of Mazatlán, on the Mexican mainland's Pacific coast, heavily exploit the commercial fisheries of the southern gulf. Many marine organisms can only survive within a particular salinity range, which makes salinity a notable factor in determining the types of potentially commercial organisms found in the gulf. The mean annual ranges of salinity of the Sea of Cortez are between 3.5 and 3.58% at the surface. Furthermore, the salinity of the water of the northern gulf is generally higher than the central and southern faunal regions due to the increased amount of evaporation that occurs in that region. Locals have alleged the existence of a giant creature known as the "Black Demon" ( es, El Demonio Negro) of the Sea of Cortez. It is usually considered to be a black shark, and less commonly as a whale, measuring about , similar to the estimated length of the megalodon. It is one of a number of alleged cases of giant sharks in the Pacific Ocean, made throughout the 20th and 21st centuries.

See also

* List of western shore communities on the Gulf of California * List of eastern shore communities on the Gulf of California * Ferdinand Konščak


Further reading

* Studies by researchers, on both sides of the border, on the threats to the diversity of species in the gulf's waters. * An anthology of writings that describe Baja California, and the Gulf of California, from sources dated from the mid-sixteenth century to present.

External links

CEDO Intercultural

Desert Museum

Friends of Wild Baja conserves and protects the critical habitats and biodiversity of The Gulf of California
{{DEFAULTSORT:Gulf Of California Gulf of California, Gulfs of Mexico, California Gulfs of the Pacific Ocean, California, Gulf of Pacific Coast of Mexico Landforms of Baja California Landforms of Baja California Sur Landforms of Sonora Landforms of Sinaloa Colorado River Ecoregions of Mexico Temperate Northern Pacific World Heritage Sites in Mexico Cenozoic Mexico Cenozoic rifts and grabens Origin of the name California