The Sea of Cortez

Beginning 25 to 30 million years ago, a section of the earth's surface lying along what we now call the west coast of Mexico began to move north and west. Pressures from the great North American and Pacific plates colliding with one another gave birth to this movement, part of the now famous San Andreas Fault system.

A sea began to grow along this widening and deepening gap. Over the millennia this sea has spread hundreds of miles to the north as the fault movement has continued. The area to the west of this fault has been forced upward, forming the rugged, beautiful mountains and peninsula of Baja (Lower) California.

Today the sea stretches 700 miles roughly north-south, averages a little under 100 miles wide, and opens to the Pacific on its south end. A combination of latitude and currents has produced what is arguably the biologically richest body of water on earth. Over 800 species of marine vertebrates and over 2000 invertebrates inhabit or visit this sea, including corals, tropical fish, sea lions, sea turtles, dolphins, and whales. At certain times and places during the year whale watchers can find orcas, sperm, gray, and behemoth blue whales (averaging 75 to 80 feet in length and 110 tons, the largest mammal and perhaps the largest animal ever).

The name for this area since the early colonial period has been the Sea of Cortez ("Mar de Cortez"). At times this name has competed with "Mar de Vermijo" (Vermillion Sea), possibly in reference to the color reflected from very large numbers of pelagic crabs. Yet despite the Mexican government's choice to place the name "Gulf of California" on maps in the early 1900's, the Sea of Cortez has remained in common usage to today, in honor of the well known Spanish Conquistador Hernan Cortez.

Cortez was among the first European settlers in the Caribbean islands following Columbus's discoveries, and went on to lead the initial Spanish conquest of the Aztecs and Mexico. Motivated by finding a northerly passage from Europe to the west coast, Cortez himself financed four expeditions by ship, the second of which resulted in the documented discovery of the sea and of the "island of California".

Cortez himself led a third expedition in 1535 to this "island", the first serious attempt to establish a colonial settlement in Baja. After some exploration of the interior, exhausted and close to starvation, Cortez and his group were forced to withdraw two years later from their site at Pichilingue (just east of present day La Paz). Cortez funded a fourth tour of exploration, lead by Francisco de Ulloa in 1539. This effort led to the first relatively detailed exploration of the coastline of the sea, including the discovery of the mouth of the Colorado River (Rio Colorado). The expedition established that the peninsula was just that, not an island. Ulloa was also able to explore a portion of Baja's Pacific Coast.

The Spanish government paid little attention to the findings of these explorations, preferring to focus on the lucrative Galleon route west across the Pacific to the Philippines. Cortez, with finances much depleted, eventually returned to Spain to complete his years.

The Sea of Cortez may be divided into four zones. The northern quarter is relatively shallow and highly saline, and is subject to tidal surges to 10 meters. The next zone to the south (including two major islands at the latitude of the Bahia de los Angeles) is deeper and has strong currents. These currents bring nutrients to the surface and aerate the water, producing high biological activity and excellent fishing. Water temperatures begin to drop significantly in the third zone (south to roughly La Paz), though all the Sea is characterized by a tropical or subtropical temperature regime. The fourth zone is oceanic in character, containing submarine canyons.

The Sea of Cortez is bounded by intriguing, and at times, dramatic scenery. Of particular interest is the Baja coastline, with an escarpment of uplifted mountains fronting the Sea and occasional necklaces of offshore islands. Your Holland America cruise will be exploring a portion of this area, from Loreto in the north to Cabo San Lucas in the south.

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