10 Geological Facts About San Francisco Bay

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Karl the Fog over the Golden Gate Bridge

From its colorful history and resilience to economic turbulence, San Franciso remains a hot spot for tourists from all over the world. Beyond the streets filled with cable cars and Victorian architecture, the city’s most defining feature is the beautiful Bay it sits beside. Here are ten facts about San Francisco Bay to inspire you to hop aboard Bay Voyager and experience in person. 

  1. More water flows in and out under the Golden Golden Gate Bridge in one day than over Niagra Falls in one week. The maximum daily flow of water under the Gate and into the Pacific Ocean is estimated to be seven times more than the flow of water at the Mouth of the Mississippi.
  2. Treasure Island is human-made, while Yerba Buena, Angel Island, and Alcatraz are natural features of the area. 
  3. Most of the San Francisco city waterfront is a landfill. Buried under what is now the Financial District are hundreds of ships abandoned during the gold rush.
  4. When discovered, Alcatraz was initially named “La Isla de Los Alcatraces” or “Pelican Island” due to the large population of pelicans that roosted on there. Today, seagulls and cormorants call the island home. 
  5. At its widest, the San Francisco Bay is 13 miles across. At its deepest, the Bay is 357 ft. The average depth of the Bay is 1 ft.
  6. San Francisco is a cool city with an average high of 64°F and a low of 51°F. Frequently the summer months are colder than the winter months because of the city’s unique climate.
  7. San Francisco Bay’s average water temperature is 56°F due to cold ocean water upwelling along the coast.
  8. The upwelling is also responsible for the city’s signature summer fog. This fog occurs when warm air blows over cool land or water and is incredibly persistent even when it’s windy.
  9. San Franciscans have named this fog, “Karl the Fog.” Scientists call it advection fog. 
  10. Beyond its summer fog, San Francisco is also a very windy destination. Due to the city’s geography and climate, the afternoons in summer months see consistent wind speeds from 25-35 knots per hour. This wind makes the Bay an excellent playground for sailors, kite-, and windsurfers, but it’s a bit blustery for landlubbers. 

Experience San Francisco Bay from the best seats in the house and book your spot on Bay Voyager. See tour options here and visit our schedule to reserve your tickets. 

Sources:

Encyclopedia Brittanica