On clear days, the skyscrapers in San Francisco are visible, as are Alcatraz , the Golden Gate bridge, various radio towers, Mount Tamalpais, etc. The deepest part of the Bay is right under the Golden Gate Bridge, with 330 feet of water. Also, regular dredging of the shipping channels is necessary, so that all the big container ships and oil tankers coming into the Bay do not run aground. The gravitational force acting on all objects on Earth, winds and the spinning of Earth around its own axis cause large bodies of water to move in certain, well-known directions. These horizontal movements of water are called currents.
Tides are the relative high and low water levels.
These four distinct stages are repeated everyday during the moon s 24 hour orbit around the Earth. The movement of water is caused by the relative gravitational pull acting between Moon, Sun and Earth, literally pulling water away from its location on Earth. Inside the Bay, currents and tides result in whirlpools and gyres. The tides for any given area can be calculated and are published in tide tables. We also get close to another East Bay landmark, the Berkeley Pier.