For the best wild swimming spot in San Francisco, ask the Dolphin Club

Diane Walton clearly remembers the first time she plunged into the frigid waters of the San Francisco Bay, almost 20 years ago. “It was so cold that I thought my organs might explode!” the 73-year-old says, her long, grey hair streaming behind her as we sit on a wooden jetty basking in the bright, mid-morning Californian sunshine. One of the local sea lions strung out along the sand barks a laugh as if in response.

Today, the water lapping at our ankles is a brisk 12.7C. But you wouldn’t know it from watching the swimmers around us, who are snapping on goggles and whooping happily as they wade easily into the Aquatic Park, an urban beach on San Francisco’s northeast shore.

As regular as clockwork, Diane swims here four times a week against the cinematic backdrop of the Golden Gate Bridge. This morning, though, in her role as president of the Dolphin Club — a volunteer-run, open-water swimming and rowing organisation founded in 1877 — she’s showing me around the club’s handsome mahogany boathouse, which sits at the head of the jetty.

Originally a men’s-only fraternity, in more recent decades it has evolved into the Dolphin Club — one of only two remaining swimming clubs in the city. Women now

make up almost 40% of the 2,000-strong members, who range in age from 18 to 94 years old. And, while the club has working-class roots, today it represents a diverse cross section of San Franciscans — there are young tech bros and ageing hippies sharing the sea with an ever-changing roster of in-the-know visitors, who are admitted three times per week.

“When I’m out there swimming, the mundane conversations that whirl around in my brain just dissipate,” Diane says as we watch a young woman in a black bikini dive beneath the water. “It’s like a miracle.”

She explains how she often shares the sea with herons, sea lions, harbour seals and sharks — “but just the tiny guys,” she says with a reassuring smile. She adds: “We’re a remarkably diverse bunch who come in all shapes and sizes — this is a safe space for all.”

While, admittedly, it’s still considered a little leftfield to plunge into the bay, San Francisco has long been shaped by the water. Today, wineries such as Treasure Island, on a tiny islet that once hosted a naval base, are utilising the high humidity and cooling mists to create unique small-batch tipples, while downtown a number of restaurants are getting creative with the ocean’s spoils. One of the standouts, Chīsai Sushi Club, has incorporated the invasive purple sea urchin into its menu, allowing diners to restore the ecosystem while they feast.

Many of the Dolphin Club’s members have been swimming in the bay for decades — some for 60 years, she says. “All the research will tell you that the people who are happiest are the ones who are physically active and have community,” Diane says, as a twentysomething man nearby performs star jumps to warm up at the seashore.

I spot Quinn Fitzgerald strolling along the pier towards us, wearing salmon-pink trunks and sipping a takeout coffee. I’ve never swum anywhere more taxing than a heated pool, so Quinn has offered to buddy up for my cold-water swimming debut — or be my “Bay-doula” as he prefers. “You’ll have a transformational experience,” he promises with a knowing smile as we pad across the chilly sands in our swimwear. I’m still feeling undecided — we’re diving in without wetsuits, which Quinn feels detract from the authentic experience.

As the water rises past my waist, it feels as if the air is being snatched from my lungs. Perhaps noticing my expression, Quinn starts running through the history of the city’s swimming clubs as a distraction. He tells me they started life during the Gold Rush era, when ordinary civilians would greet passenger ships docking from Europe, dashing across the water to be the first to help the VIPs to shore on the promise of a hefty tip. Behind me, I can hear the cable-cars dropping tourists off at nearby Hyde Street Pier.

Then, all at once, it hits me like a wave. Having submerged my shoulders and paddled a leisurely loop, I start to understand the magnetism of this water, which is clear enough that I can see the sandy ocean bed shimmering below. A light-headedness is beginning to creep in, then a clearing of the mind, followed by a rush of euphoria. I get it, I tell Quinn excitedly.

He grins. “Next, you should try swimming to Alcatraz,” he says, filling me in on the 40-year-old New Year’s Day tradition that sees a school of 99 hardy swimmers, from the Dolphin Club and neighbouring South End Rowing Club, racing from the notorious prison island back to shore in a brisk 1.25-mile crossing.

“Alcatraz is probably the most iconic open-water swim globally,” he says, lazily treading water in the direction of the shore. “It really captures the imagination — the fact that it was a prison and that escaping from it has long been mythologised.” Back on land, our hero’s welcome is the Dolphin Club’s inviting sauna.

Inside the cosy pinewood den, the benches are lined with swimmers of all ages, who are studiously mapping out various seafaring routes and discussing the tidal tables. Steam rises from our thawing skin and a sense of easy camaraderie fills the tiny room. A couple of the old-timers even crack open beers.

This morning, each of us had stripped down and — against our intuition — plunged into San Francisco Bay and emerged feeling completely invigorated. As Quinn puts it, “anyone who experiences the waters of this bay always leaves a better person”.