Heading out: A surfer paddles back out of the bay at the Mavericks contest
From 8am the small band of pros have been competing in six-man groups, as judges marked them on the quality of the wave, difficulty of the drop and overall performance.
The surfers wait for their perfect wave about half a mile from shore, and have spare boards tied up near by. On the beach, crowds of spectators line up to watch and enjoy the festival that takes place around the competition.
Because the contest is held only when the famed monster breaks are expected to roll in, no one is sure from year-to-year when the next event will be held, and surfers have just 48 hours' notice.
Despite being only open to the most experienced surfers, two pros have died at the bay, including the legendary Mark Foo from Hawaii, who drowned there in 1994.
Jamie Sterling, who traveled from Hawaii to take part in Friday's event, told SF Gate: 'You can't compare this place to Hawaii. It's got cold water, giant sharks, giant waves and giant rocks. It's like nothing else.'