[2] Cordell Bank is one of the United States' 13 National Marine Sanctuaries that protect and preserve ocean ecosystems in the U.S. Cordell Bank is a seamount approximately 50 miles (80 km) northwest of San Francisco where the ocean bottom rises to within 115 feet (35 metres) of the surface.

The unique blend of ocean conditions and undersea topography creates a rich and diverse underwater ecosystem.

The prevailing California Current flows southward along the coast, causing an upwelling of nutrient-rich water that provided the foundation for the area's marine ecosystem.

Cordell Bank was originally created 93 million years ago, as a member of the Sierra Nevada.

Eventually this grinding carried Cordell Bank to its present location opposite Reyes Point.

Coastal California has a rich history of marine utilization by Native Americans and early settlers.

[6][7] In 1869 Edward Cordell (the reserve's namesake) was sent to collect additional information on a "shoal west of Point Reyes".

The efforts gave rise to an understanding of the biodiversity of the bank, and were instrumental in the decision to make it a sanctuary.

[10] Twenty-six species of marine mammals, including whales, dolphins, seals, and sea lions, are known to frequent the waters of the sanctuary.

In addition, Cordell Bank is one of the most important feeding grounds in the world for the endangered blue and humpback whales; these species travel all the way from their breeding grounds in coastal Mexico and Central America to feed on the krill that aggregate near the bank.

Other visitors include California sea lions (Zalophus californianus), northern elephant seals (Mirounga angustirostris), northern fur seals (Callorhinus ursinus), and Steller sea lions (Eumetopias jubatus), all of which are attracted to the abundance in krill, squid, and juvenile fish.

It is also one of the few places to see a short-tailed albatross (Phoebastria albatrus), which is extremely rare; the species was thought to have gone extinct after World War II.

[12] During the winter storm months, the sea is dominated by rough weather, which mixes the deeper water with that above.