THE PLUNGE: Maverick Swimmers, an Unlikely Quest, and the Transformative Power of Cold Water

Ice swimming occupies a strange frontier at the edge of our sport, equal parts fascinating and intense. Thankfully, Chris Ballard captures this icy world with a reporter’s curiosity in THE PLUNGE: Maverick Swimmers, an Unlikely Quest, and the Transformative Power of Cold Water.

Ballard, a senior writer at Sports Illustrated and an award-winning author, didn’t simply drop into the ice-swimming scene and call it reporting. He spent three years chasing cold water across Norway, Finland, Ireland, Italy, Boston, and Copenhagen, immersing himself in the culture rather than observing it from the shore. Along the way, he became an age-group national champion in ice swimming and competed at the Ice Swimming World Championships in Italy.

The result is a deeply reported, entertaining, and often surprising look at a sport that pushes the limits of endurance and resilience.

THE PLUNGE releases, today, June 9 and is available from Simon & Schuster and major booksellers everywhere.

Cover and book excerpt from THE PLUNGE by Chris Ballard. Text copyright (c) 2026 by Chris Ballard. Reprinted by permission of Simon & Schuster. All rights reserved.

BOOK EXCERPT, THE PLUNGE 

CHAPTER 8

The Shivers

How do you stage the inaugural national championship of a sport no-body’s heard of?

This was the issue now facing Joe and the board. Among a host of lo-gistical and marketing hurdles, the biggest by far was finding a location. After years of holding IISA events in open water, Ram wanted to gravitate to pools. For starters, they reduced risk and allowed for a smoother competition: no ice, no current, walls to push off from. Equally important, if you wanted to catch the attention of anyone even remotely involved with the Olympics, you had to prove that your times—and records—were standardized. Usain Bolt’s mark in the 100 couldn’t be eclipsed by some dude on a dirt track.

But good luck finding an outdoor pool in the United States that both stayed open through the winter and dropped below 41°. Who knew if you could even keep a pool open through the winter without damaging it? In addition, it had to be an Olympic-standard 25-meter pool, not 25 yards like most American pools, because IISA is a global organization, and the U.S. is one of only three stubborn countries, along with Liberia and Myanmar, that hasn’t switched over to the metric system.

Joe had an idea, though, even if it was a long shot.

He put in a call to his childhood swim club, Brookfield, and got the current director on the line.

“I’ve got a weird favor to ask,” he said.

*  *  *

Meanwhile, I faced a different challenge. In a moment of bravado, I’d told Joe I’d take him up on the offer and swim at Nationals.

By this point, I’d already begun dabbling in cold exposure, beginning the way most people do: by standing in the bathroom, cranking the shower handle the wrong direction, and stepping in.

The first day, I huffed and puffed, counting the seconds until—wham!—I felt it, what Rex Butler, the athletic trainer, had called, “that huge dump of dopamine and adrenaline.” No wonder author Ian Fleming had James Bond finish his showers cold.

By day five, I exited the water feeling like a superhero, whereupon I bounded down the stairs, made breakfast for the family, and started a morning dance party.

Soon enough, I began to look forward to the showers—or at least the feeling after. Within a couple of weeks, I’d settled into something of a rou-tine. My family was amused and, I think, a bit intrigued. One day I heard Metallica’s “Enter Sandman” blasting from our downstairs bathroom. A few minutes later, my older daughter, Callie, emerged red-skinned and wild-eyed, announcing she’d also just taken a cold shower and she was now “VERY FIRED UP, DAD!”

Around the same time, wanting to try out the recovery protocol An-thony Katz first told me about, I found a gym with a proper plunge tub and timed my visit to coincide with recovery from an over-35 hoops league game the night before—the middle-aged weekend warrior’s equivalent of an NBA back-to-back. I’d awoken stiff and sore. My hip ached, and the plantar fascia on my left foot felt like someone was holding it over a Bunsen burner.

The water was 48°, plenty brisk to take my breath away. Three rounds of plunging later, the pain in my hip and foot was a distant memory. Men-tally, I felt like I’d cleared my cache. I was sold.

Still, it was a far cry from ice swimming.

*  *  *

For New Englanders, training to ice swim is relatively straightforward: Start in the summer, continue into the fall, and then “swim down the sea-son,” as Elaine Howley puts it. As the water temperature gradually drops, you gradually acclimate.

But I lived in the Bay Area, where the Bay “only” dropped to the low fifties in the winter. Swimming down the season could only do so much. Same for occasional bouts of exposure—like when, during a family hike in Lassen National Park, I’d diverted us off the trail, bushwhacking down to a creek fed by fresh snow runoff for a brief, humbling dip (“Is this what it feels like to be attacked by piranhas?” I wrote in my notebook).

Clearly, I needed a better training approach.

I thought of Joe’s freezer. Converting one looked doable—according to the internet, you could use a pond liner, or a truck sealant—but I wor-ried about owning a large, electrified, jury-rigged appliance full of water in a house with two teenagers. As for the commercial plunges, they looked great, but even the low-end ones cost upward of $4,000.

Then I came across the handiwork of the Hodge brothers. The Texas-based siblings started out selling hot tubs. Worried that Jacuzzis had ac-quired a “retiring grandparents” vibe, as Jesse, the elder Hodge, puts it, they named their company Modtub, short for “modern hot tub.” They hoped to appeal to a younger, hip audience.

Then one day they saw the Plunge guys’ appearance on Shark Tank and sensed a nascent market. That weekend, Jesse began tinkering with how to build a cold plunge. From experience, he knew roto-molded plastic pro-vided the best combination of insulation and leak protection. Fabricating their own would be expensive and labor-intensive. But what if they instead adapted an existing plunge-shaped, insulated product?

Like maybe a big-ass cooler.

After trying out the Yeti Tundra (“coffin-shaped, too small”) and the Icey-Tek (big enough but too expensive), they landed on the Grizzly 400. At roughly 4 feet by 3 feet and 91 pounds empty, it’s a beast, popular with ocean fishermen and hunters, who use it to store deer. To convert it, the Hodge brothers drilled holes, added circulation tubing, and attached a 1/4-horsepower chiller and a water-filtration system. The result: a func-tioning cold plunge. After securing a relationship with Grizzly, they put their price point under $3,000 and launched in February of 2023, hoping to capitalize on the growing market.

Orders trickled in at first and then picked up—from fitness facilities, home users, CrossFit gyms, and, to their surprise, fire stations. A few cus-tomers used it for chemo or Parkinson’s. Veterans got it to treat PTSD. To meet demand, they rented a warehouse and office space in Dallas, not knowing how long their window would last. “I hope it’s not three years from now and people are saying, ‘Remember when everyone bought cold tubs?’ ” Sawyer, the younger Hodge, said. “At the end of the day, it’s just cold water.”

Indeed, and that was exactly what I needed.

I put in my order, hoping the tub would arrive before Nationals.

In the meantime, I needed to see my doctor.

Since Ram launched IISA, he’d made a point to stress safety. Knowing one serious incident could scuttle any chance of an Olympic berth, he’d continuously upped the requirements. By the time I printed out the med-ical forms in the fall of 2023, they ran eight pages and required a thorough checkup: abdominal, cardiovascular, neurological, respiratory rate, oxygen saturation, blood pressure. In addition, I needed to get an EKG and fill out a comprehensive medical history, including past surgical, neurologi-cal, and ENT procedures. Did I have parents/siblings with cardiovascular conditions? Any psychiatric issues? Had I been refused life insurance? Om-inously, I needed to provide next of kin. And, finally, a waiver.

“I am aware that an ICE Swim is an extreme challenge, mentally and physically . . . I hereby acknowledge that the Swim is done at my own risk, I understand all risks involved and I hold none involved in my Swim attempt responsible for any mishap that may occur to me because of this Swim.”

It was grim stuff, but it also served the purpose: a reminder that this was serious. And, more important, you’re the crazy bastard choosing to do it. It’s on you if it goes sideways.

I headed to my doctor.

He welcomed me in, then riffed through the forms, smile turning to bewilderment.

“So you’re going to be swimming in water that’s forty degrees?” “Yeah, that’s the idea.”

“And you haven’t done it before?” “Correct.”

Two hours and many tests later, he cleared me. “Just be careful,” he said as I walked out the door.

I intended to. There’s a reason Tipton, the British naval scientist, has spent much of his career trying to get people not to go into cold water, running dozens of studies and coauthoring the go-to resource of the realm, Essentials of Sea Survival. Sure, most of the danger comes from the environ-mental factors: dropping core temps, hyperventilation, slipping on ice, the uncertainties of open water. But there’s also an individual element—how your body handles the shock. People with underlying heart conditions, especially arrhythmia, are at risk. Diving into very cold water is particularly unwise, especially if you’re not acclimated. This creates what Tipton calls “autonomic conflict” as your heart rate spikes (the fight-or-flight response) while, at the same time, the immersion signals your body to try to slow your heart down to preserve oxygen.

Even plunging—largely a safe activity, according to doctors I spoke to—can be dangerous if you’re not smart about it. In particular, a handful

of people have died, apparently after using a breathing technique similar to Wim Hof’s in or near water (never, ever, ever do this). The potential danger of Hof’s method is that hyperventilating and breath-holding causes carbon-dioxide levels to drop, dulling the body’s urge to breathe; if oxygen levels fall too low, it can lead to blackouts. If someone is lying on a carpet or a couch—where you’re supposed to do the breathing—no ill should come of it. But alone, in water, blacking out can lead to drowning.

Hence the cardinal rule of cold-water swimming: Never go in alone. This has a side benefit: camaraderie. Open water swim groups are famously welcoming and inclusive, in part because they have to be. You all rely on each other, and each time you brave that cold water, you are, in essence, voluntarily entering a low-level crisis together. Afterward, flush with feel-good chemicals from the exercise and the cold, you all celebrate because you made it through. “It creates a social connection because it really is like shared trauma,” Elaine told me. Then she laughed. “Three beers does sort of the same thing, but this is a lot healthier.”

By December, I was preparing in earnest.

I joined a local open water swimming group and began heading to the Bay on weekends, wading into the water just after sunrise, as an orange glow spread across the waves.

On the advice of swimmers, I invested in a Dryrobe, basically a luxurious wearable towel with a hood and waterproof exterior. It provides warmth, protection, a portable changing room, and instant post-swim garb.

During the week, I took to the pool to practice the 50 and 100 free—my two events—using the big digital clock on the wall for timing. What I didn’t practice: flip turns or “underwaters”—the sleek, submerged dolphin kicks swimmers use after each turn. They’re banned in ice swimming, to reduce the amount of time your head is underwater. Same goes for diving in from a block. Instead, swimmers begin with one hand on the wall and the other stretched forward, then use an “open turn” to spin and push off in the opposite direction.

Swimming itself was the easy part of my preparation—at least com-pared to acclimation. Thankfully, the Modtub arrived by early winter, and I installed it in a corner of the backyard, where it looked like, well, a giant cooler in the corner of the backyard. It worked, though; I could comfort-ably sit in it, submerged to my clavicle, knees bent in front of me. After be-ginning at 55°, I worked my way down to the high 40s, staying in a minute or two at first. Within a week, I got it down to 39°, just under the official ice swimming cutoff—and as low as the chiller would go.

It wasn’t easy, but it also wasn’t as hard as expected. It turns out our bodies are remarkably adept at this type of systematic acclimation. At one point, Tipton and Golden ran a series of studies and found it only takes five days of cold exposure, at two minutes a session, to cut the hyperventi-lating response nearly in half—and by day seven, it’s only a third (they later discovered you can actually do all this exposure in one day, in bouts, if you want). Your heart still races, but you spend less time huffing and puffing, which is particularly helpful if you’re about to sprint a 50-meter freestyle. Remarkably, much of this adaptation sticks around for up to a year.

From a survival perspective, deliberate exposure makes sense for anyone working around cold water: rescue teams, Navy SEALs, Marines. Many sailors instinctively realized this. During World War I, Admiral John Jelli-coe of the Royal Navy took the precaution of “subjecting himself to daily cold-water baths” when not engaged in battle. These days, military units in countries like Norway often include intensive cold-water training for troops.

Essentially, I was doing a much less heroic version of the same thing. As I did, I thought about scaling those mental walls Huberman mentioned. The first wall reliably erected itself during that moment, in my warm bedroom, when I decided whether to get on with my day or put on my swimsuit. The next came when I stood outside next to the tub, in the gray morning light, still fully capable of retreat. The third wall loomed once I got in—and all the alarm bells rang. Then, reliably, magically, around the ninety-second mark, the experience went from unpleasant to . . . weirdly pleasant? By minute three I’d relaxed into it and felt like I could sit there forever. Unless, that is, I moved.

It seems counterintuitive—you’d think moving around would warm you up. But when I did, a rush of cold returned, the product of an evo-lutionary relic. You see, our bodies are surrounded by what’s known as a “boundary layer” of molecules that move slower than normal and are less prone to disruption. You can think of them as a tiny force field around you, keeping you warm. Stay very still, and your body will heat this boundary layer, whether it’s air or water. Cold-weather animals rely on it for sur-vival, increasing the amount of trapped air by raising their hair or puffing up their feathers to create a tiny microclimate around themselves. This is why we get goose bumps; our evolutionary defense mechanism is kicking in, trying to raise hairs we (mostly) no longer possess. Instead, since we’re basically underdressed mammals, our boundary layer is only a few milli-meters thick.

That’s still enough to keep you warmer than you would be otherwise, though. Which is why, in a sea survival situation, your best bet, counter-intuitively, is to stay as motionless as possible as you await rescue. The same goes in a cold tub. Sit very still, and you’ll feel warmer—because you are.

In my case, as I increased the length of my sessions in the tub, I would notice a reliable pattern: The first two minutes were the most challenging, after which a calm descended. During this time, I’d stare at the reflection of the trees in the water and center myself for the day. Once I got out, a pleasant chill stuck with me for the rest of the morning. It became my most productive work time. Energized, focused.

*  *  *

This progression—from wired to meditative—is the work of something called the vagus nerve. People in the cold-water world reference it fre-quently, often with a kind of mystical reverence, but no one seemed to know exactly what it was or what it did. So I called Dr. Imanuel Lerman, a neurologist and pain-medicine specialist at UC San Diego who’s spent years developing and studying vagus nerve stimulation technologies.

To start, he explained, the name is misleading. A “vagus nerve” sounds like a single strand in a single place. In reality, it’s a bundle of tens of thou-sands of nerve fibers that run on either side of the neck, alongside the carotid arteries and jugular veins. These bundles function as the body’s communication hub, relaying vital information between the brain and the organs. They’re also the brake on the fight-or-flight response.

This is particularly noticeable underwater. Upon submersion, the vagus slows our heart rate to conserve oxygen, buying us as much time as possible. But plunge into icy water and the cold shock response creates an immediate conflict: all that panicked gasping. This is where the vagus per-forms a remarkable trick. Within moments, it overrides our physiological alarm systems, essentially telling the body that, despite appearances to the contrary, it’s time to calm the F down. So, within seconds, heart rate drops while blood vessels constrict, bringing on that Zen state. This sequence is what’s known as the mammalian diving reflex, a primal mechanism we share with seals and whales. It’s so powerful that Per Scholander, a Swedish-born physiologist who studied diving mammals, dubbed it the “Master Switch of Life” in a seminal Scientific American article on the phenomenon in 1963. The diving reflex is why a three-month-old will reflexively close their airway and lower their heart rate underwater, why free divers can stay down so long, and why sticking your face in a bowl of ice water can help calm you. Recently, influencers have been doing this to “reset” their ner-vous systems. It turns out that, no, they’re not full of shit.

A team of German researchers ran a study, published in 2022, in which they intentionally stressed out college students after cooling their faces to see what happened. To do this, they employed an old research standby, the Montreal Imaging Stress Task (MIST). Here’s how it works: Students sit at a computer, cranking through endless math problems while an “instruc-tor” occasionally hovers with a stopwatch, sighing or shaking their head when answers come too slowly (even if they don’t), and saying things like, “Your performance was much below what we had hoped for.” Reliably, this spikes heart rate and cortisol—the body’s main stress hormone.

But by pre-cooling the face, the researchers found they could blunt this response. When the cold hit the trigeminal nerve, which branches across the forehead, cheek, and jaw and functions as a thermal sensor, it spurred the vagus into action. As a result, not only did putting on a freezable face mask drop heart rate 20–27%, but the cooling also had a powerful effect on cortisol. For those in the control group, without cooling, levels shot up by 71% during the stress test, as you’d expect given the MIST’s freak-you-out design. But for those who’d cooled their faces, their cortisol didn’t budge—less than a 1% rise on average—despite the hectoring supervisor. In other words, dunking your face in ice water, or in this case applying an ice pack to the eyes and forehead, accomplished something even breathing exercises and meditation often can’t: It calmed the body quickly and effectively. As the study’s lead author, Robert Richer, noted to me: “What else makes you both alert and relaxed?”

Now imagine your whole body entering cold water. At first, everything spikes: heart rate, blood pressure, cortisol. Then the calming vagus signal helps bring much of this back down. That’s why winter swimming is both exhilarating and strangely calming.

And it seems the more you do it, the better your body gets at it. Dr. Ler-man explained that with regular exposure, “you also train the vagus to reg-ulate more,” similar to a muscle. Over time, this builds what scientists call “vagal tone”—an indication of the body’s ability to quickly shift into calm states after stress. One study found that higher vagal tone is consistently associated with better emotion regulation. Others have linked it to lower systemic inflammation and lower risk of all-cause mortality.

It didn’t take long for me to experience the effects of acclimation. About a month after getting the cold tub, during an early morning plunge, I made it to six minutes at 39°. My feet were numb when I got out, but I felt a surge of accomplishment. I headed inside.

“SIX MINUTES AT THIRTY-NINE DEGREES!” I announced, as if I’d just summited Everest.

Confetti did not fall from the ceiling. “Yay?” said my wife.

I didn’t care. I was jacked up. I did something hard.

A few minutes later, despite being inside, and clothed, my teeth began to chatter. This was it—the afterdrop Lynne Cox had warned Ram about. Now that I was out, in a warm place, the blood pooled in my core was circulating again. As it did, it drew the cold blood from my extremities back toward my center, producing a chilling effect. This meant that even though I was dry and in a warm room, my body temperature continued to drop even lower.

Time for phase two of the body’s self-preservation playbook: shivering.

Or as Professor Mercer puts it, “Turning on the heater.”

I’d experienced this after some of my longer Bay swims, when I’d emerge onto the beach, feeling fantastic, and then start chattering like a windup toy. The more I learned, the more this made sense. Body fat has roughly the same insulating properties as cork—4 CLO per inch of fat for those scoring at home (where CLO indicates clothing’s insulation value). Not only was I long-limbed and lean—making me a laggard on the CLO scale—but I was also stuck with Raynaud’s disease, an annoying but largely benign condition wherein extremities numb unusually fast. Hence, I got cold quickly and shivered a lot.

Taken to the extreme, this can be an issue. Irish ice swimmer Ger Ken-nedy, a jovial ex-rugby player, once overdid it on one of his early cold swims and came out shivering like crazy. He huddled in his Jeep with the heat on before trying to drive home. Eventually, a squad car pulled him over be-cause he was driving so erratically. Recalled Kennedy: “They saw me with about twenty jackets on, shaking like mad, blue-looking, and the cop says, ‘What is wrong with this fella?’ ”

“I told them, ‘I’m not drunk, Garda, I’m sorry. I’ve actually been swimming!’ ”

As inconvenient as it may be, shivering is actually remarkably effective. It begins when your hypothalamus—the brain’s thermostat—senses the change in core temperature and sounds the alarm, directing motor neurons to trigger a battalion of tiny skeletal muscle fibers to fire in short, staggered bursts, contracting ten to twenty times a second, like a team of backup generators kicking on after a blackout. Each twitch produces friction, and friction means heat. Your body essentially burns calories just to keep the pilot light burning. The colder you are, the more intense the contractions. At first it’s intermittent. But as your core temperature drops, it ramps up into full-body tremors—what Kennedy experienced—that can crank your energy output up to five or six times resting levels, allowing you to reach a staggering 46% of your aerobic capacity: the equivalent of going for a jog, only performed entirely by involuntary muscle action. Which is why the real calorie burn of winter swimming isn’t necessarily the swimming itself—though of course that burns calories—but the rewarming.

The calendar turned and I assessed my status. In five months, I’d progressed from showers to Bay dips to home plunges. I’d put in the work in the pool and even improved my times, which, at an age when performance in most sports can be tracked on a steep downward trajectory, was almost embar-rassingly exciting.

Even so, when it came to ice swimming, I felt woefully unprepared—primarily because I had yet to actually ice swim. The closest I got was two kinetic minutes in Lake Tahoe a month earlier, the water temperature at a relatively balmy 46°. I felt a twinge of guilt, knowing the lengths other swimmers went to prepare. When Lynne Cox trained to swim the English Channel, for example, she stopped taking hot showers, slept with the win-dows open, and ditched her blankets at night. Ranie Pearce, a Bay Area open water swimmer, made the six-hour round-trip drive to Tahoe every week while preparing for her Ice Mile attempt.

Me? I did my best to mimic an ice swim in my yard, sitting in the tub at lip level and “swimming” with my arms. It’s unclear how well this simu-lated actual swimming, but it did a bang-up job of displacing about a third of the water from the tub. I also must have looked ridiculous—a grown man sitting in a large plastic cooler full of water, doggy-paddling in place and breathing heavily.

Not that I was thinking about that. One of the best things about being in water that cold is you instantly stop caring how you look, what Elaine calls “the vanishing of vanity.” So I paddled and huffed and puffed. Then, intermittently throughout the day, I’d stand over the tub and dunk my head in every few seconds—like in mafia movies, only self-inflicted. Mean-while, I resigned myself to what awaited. In my training journal, when considering race strategy for the 100, I found myself writing things like, “Hopefully my face will be numb by then anyway.”

Ready or not, I caught a morning flight to DC.

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