Jumping into the San Francisco Bay without a wetsuit can feel a little bit like a punishment at first — especially during the winter, when the water temperature can drop as low as 50 degrees Fahrenheit. But if you get past the initial shock of the cold, open-water swimming in the Bay might become your new favorite hobby.

Both of San Francisco’s century-and-a-half-old athletic clubs at the edge of Aquatic Park Beach, the Dolphin Club and South End Rowing Club (SERC), have helped put the Bay Area on the map for open-water swimming internationally. People come from all over the world to swim in the Bay, with the 1.4-mile swim from Alcatraz Island to Aquatic Park — often referred to as an escape from Alcatraz because of the island’s history as a federal prison — being particularly popular. Each year, the SERC Alcatraz Open Swim alone attracts between 500 and 600 participants, many of them from outside of the U.S. 

But why would anyone choose to swim in frigid ocean water rather than a temperature-controlled pool? According to a 2020 study published in the International Journal of Environmental Research and Public Health, cold-water swimming can have physiological benefits, including decreased risk of cardiovascular illness, increased cognitive function, and improved endocrine and immune system function. 

Cold-water swimmers cite other benefits, too. “There’s literally not anything you can be going through in life that once you get out of the Bay, you don’t feel a decent amount better [about],” said English teacher Lindsey Collins, who swims in Aquatic Park without a wetsuit four times per week. 

While the Bay’s cold, choppy waters may seem intimidating, many swimmers seek the thrill of the open water and find post-swim sensations gratifying. “I really like swimming in the Bay because it gives me a sense of self-accomplishment that is hard to really get anywhere else,” said Lexie Stewart, The Nueva School ’28, who started swimming in the Bay without a wetsuit earlier this year.

“I took my brother [swimming in] the Bay a few years ago [when] he was having a really terrible day,” Collins said. “Afterward, he said, … ‘It was so cold, I wanted to punch you in the face. But now that it’s done, that was completely life changing.’”

Like Stewart and Collins, many people choose to swim in the Bay without a wetsuit despite an increased risk of afterdrop — when your internal body temperature continues to drop after exiting the water — and hypothermia. “I just want to feel the water, even when it means I can’t swim very long in the winter because I get too cold,” said Sarah Levin, library director. 

Levin frequents the Albany Bulb and Point Richmond in the East Bay, where she typically swims wetsuit-free twice per week. “I love the freedom of swimming in the Bay. I love the views. I love being in nature. I love seeing pelicans 10 feet away and I just really like the feeling of being in cold salt water,” she said. “I always tell people who aren’t swimmers that it’s similar to trail running versus running on a treadmill.”

With all the Bay Area has to offer — including a tight-knit community of swimmers and a major hub for open-water swimming right at our fingertips — everyone should try swimming in the Bay at least once. “Open-water swimming is a great way to try something new and connect with [the Bay Area] community through a unique activity,” said Aurelia Duverge, Lowell High School ’27, who began swimming wetsuit-free in the Bay as a sophomore. 

Whether you’re looking for a new form of exercise, hoping to relieve stress or just curious about what cold-water swimming is all about, swimming in the Bay has something for you. “There’s something about it that [is] truly addictive. … After you swim, you just feel amazing all day long,” Collins said. “You’re literally connected to the biggest thing on Earth, which is the ocean. … Swimming out and seeing the Golden Gate Bridge from the water, you just feel connected to something so much bigger than you.”