Tim Attell of Fairfax has swam in the Golden Gate "Sharkfest Series" twice before.
But on Monday, he crossed the finish line first, happy to have survived more than 1.5 miles of swimming in choppy waters.
"It was great. It was fun," he said.
Swimming was especially hard, he told NBC Bay Area, because of the strong tides Monday.
He said swimming in the bay with the Golden Gate Bridge as a backdrop is quite different from swimming in a pool.
"You have to be really aggressive, barbaric," he said.
Stephanie Chuang contributed to this report.