Area The
International Hydrographic Organization 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 is divided into three faunal regions: Northern, Central, and Southern. 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.)
Islands The gulf contains 37 major islands, the two largest being
Isla Ángel de la Guarda and
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.
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.
Estuaries There are a number of negative
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,
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, 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
ephemeral remnant estuary. The remaining gulf inlets still are important to several species of fishes, crustaceans, and shellfish that are commercially harvested.
Climate 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. ==History==