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Cold Water Swimming: Dean Hall's Cancer Cure

Updated: Feb 2

The record-breaking swim that healed chronic lymphocytic leukemia (CLL)


  • Diagnosed with chronic lymphocytic leukemia (CLL) and non-Hodgkins lymphoma, Dean Hall considered giving up after losing his wife Mary to a brain tumor.

  • After rediscovering a childhood ambition, Dean decided to begin training to swim the entire length of the Willamette River in Oregon. His doctor advised against it, telling him that in his weakened state, the swim might kill him.

  • In his book The Wild Cure, Dean chronicled the harrowing adventure that was his swim and the surprising health outcome. After his swim, doctors could no longer find a trace of leukemia in his blood.

'The Wild Cure'

Diagnosis: Chronic Lymphocytic Leukemia (CLL)

Three days before Christmas 2006, Dean Hall's doctor sat him down and told him, "Dean, you've got leukemia, and it doesn't look good."

"You've got features of both acute and chronic leukemia, he said, and your numbers seem to be escalating rapidly. If things don't change," he said, "and we've got to hope and pray they do, but if they don't, you got four to six weeks."

"Thankfully," Dean said, "it switched over to chronic lymphocytic leukemia (CLL)." Although CLL is untreatable, and incurable, Dean knew that it could be managed for a decade or two before it finally killed him.

That was the beginning of the journey that took Dean into the cold waters of the Willamette River in Oregon, to swim its entire length of more than 180 miles in just over three weeks.

Mary's brain tumor

By 2009, Dean had survived a life-threatening case of pneumonia. He was feeling stronger, and published a book. He felt life was good, but his respite was short-lived.

In August of 2010, his wife Mary was diagnosed with a brain tumor.

There was no treatment available that could improve her quality of life. 52 days later, she died in her sleep.

In his grief, Dean lapsed into despair.

His leukemia "came back with a vengeance," he said, "and brought with it non-Hodgkin's small cell lymphoma.

"My (blood) numbers just went crazy. So I tried to manage it as best I can or could, but I didn't really care. I kind of schlepped through my practice trying to care for these people as much as I could. I took a lot of time off because I found myself not really in a position to provide help for others."

Viral meningitis

His daughter Bre was 18 then, and worried that she might lose him, too. Thinking he would show his daughter how strong he really was, Dean swam across an Oklahoma lake, not realizing how polluted it was.

He contracted meningitis, and once again approached the brink of death.

"I had lost 60 pounds in six days and I'd been out that entire time, and I didn't recognize myself. I had lesions and scabs all over my whole body and I didn't look like myself because I'd gotten so thin and I couldn't really stand up because I was weak and dizzy, and had blindingly painful migraine," he said.

"And the worst part of this was they had to send my results, my blood work results, and some of the biopsies they took to California because they didn't know if it was viral meningitis or herpetic meningitis. And we had to wait five days praying that it would be viral meningitis, because if it was herpetic meningitis, it would continue to eat away my brain and I'd lose all my memory. And so I'd end up being somebody that would have a ten second recall. And so for five days, I laid there in the hospital with this terrible migraine thinking 'Shit, I've lost everything. Now I'm going to lose my fucking mind.'

"It was the lowest point of my life."

Dean recovered, slowly. It took him two weeks to regain the strength to walk.

The mirror

By August 2013, Dean was living alone in Oregon in what he called "a dark little duplex." He said he made a habit to avoid looking at himself in the mirror, because he didn't like what he saw any longer.

He was getting weaker again. It became a struggle just to reach the bathroom.

"I was leaning on the bathroom counter, just to kind of catch my breath," he said. I looked up and it shocked me how different I looked even from the last time I'd looked months before.

"I had red rims, swollen eyes, and the guy I was looking at looked so sad.

"It just broke my heart."

At that moment, Dean fantasized about how easy it would be to let the leukemia and lymphoma overcome him. He was tempted to "let nature take its course," and die a death no one would blame him for.

Until he thought of his Daughter, again, and told himself "I can't be so self-absorbed in my own pain that I forget her. I've got to find a way to come back!"

Into the River

For weeks, Dean prayed to find a purpose to his life that would restore his spirit.

Nothing came.

It wasn't until he was going through some old things his Mother had packed away a long time ago, and he found a childhood journal in which he written "When I get old, I'm going to climb Mt Everest and swim the English Channel."

"A shot just went through me!" he said.

The journal reconnected him with the sense of adventure he had as child, and Dean resolved to train himself back into shape to swim.

His doctor disapproved.

"Dean, you remember viral meningitis?" he asked. "You get in a public pool, it'll do the same thing. It'll kill you. You really want a temp fate twice?"

Dean told him, "I've got to do something. I can't just die sitting on a couch watching Wheel of Fortune. I got to go out swinging."

The next day, Dean started training.

After a few months, he'd worked his way up to a mile.

That's when he set his sights on swimming the Willamette River.

"I remembered 30 years, almost to the day before in 1984, I'd gotten this vision of swimming the entire length of the Willamette River," he said. "But I had put that dream away because, as a 24-year-old, I was trying to start my teaching career, build some money, buy a house, do all the responsible American adult things.

"And when I remembered that original dream, another rush just welled up within me. I'm like, yeah, I don't care if I died doing this thing. I got to do it!"

Cold water swimming vs cancer

It took Dean 22 days to swim the more than 180 mile length of the Willamette. In his book, The Wild Cure (Hall & Hall 2023) he described the hypothermia, the near drowning, and the concern that his doctor expressed after estimating his body fat at 3%.

But even more remarkable than his swim was what happened almost six months after.

Although he felt strong physically, his parent urged him to seek a blood test to monitor his leukemia. So he flew to San Diego to visit the same specialist who had overseen his diagnosis in the first place.

The news shocked him. His leukemia was gone.

"If I hadn't diagnosed you myself," the doctor said, "I would have said you never had leukemia in the first place. I've been doing this for over thirty years and I've never seen this happen. I cannot officially diagnose you with leukemia anymore."

Dean Hall went in to the cold Willamette River with chronic lymphocytic leukemia. He came out of the river without it.

Dean asked what could have caused his miraculous recovery, and of course the doctor could only speculate that it was his cold water swimming.

Since then, new research has been published that supports that hypothesis. In Ice Bath Cryotherapy for Cancer, I summarized the mechanisms by which cold therapy has been demonstrated to inhibit tumor growth. There are at least three:

  • Activation of brown fat starves cancer cells of the glucose they typically need to grow,

  • Endogenous production of ketones exposes cancer cells to a hostile biochemical environment,

  • Cold shock proteins produced during whole-body immersion in cold water facilitate the repair of damaged DNA.

Dean likely had all three of these mechanisms working in his favor during his swim. Moreover, exercise along will inhibit cancer cell proliferation, regardless of temperature. For example, when cancer cells are exposed to blood drawn from healthy just after exercise, the exhibit reduced survival (Soares et al. 2021, Kurgan et al. 2017). In other words, Dean was getting the benefit of the cold and the strenuous exercise, stacked together.

Finally, one of the best things Dean may have done for his mitochondria during his swim was take a weekend break. After more than two straight weeks of swimming an average of about 10 miles a day, Dean's doctor urged him to take a couple days off.

"But that will 'll put me behind," Dean complained.

He doctor asked, "Behind what?" and Dean took a break.

What happened during that time when Dean was resting and eating and regaining his strength may have been mitobiogenesis -- i.e., the creation of new mitochondria. As I wrote in Mitochondria, Cold, Recovery from Cancer, the mitochondria are essential for providing the energy necessary to power healthy cells. Ordinarily, exercise and cold exposure both stimulate mitobiogenesis to improve metabolism. Nonetheless, overdoing either can leave mitochondria in a damaged state without time for recovery.

Finishing off the lymphoma with forest bathing

There was only problem after Dean tested negative for leukemia: his lymphoma was worse. The specialist recommended chemotherapy.

Dean preferred to visit the forest.

In Japan the practice of forest bathing is known as shinrin-yoku and Dean had read about scientific studies that show it promotes healing, improves mood, and contributes to a general sense of well-being. The mechanisms are uncertain, but Dean was convinced that breathing the phytoncides released from trees would be beneficial for his immune system. He decided he'd spent at least one night a week in the forest, instead of several rounds of chemotherapy.

He's blood numbers started going in the right direction almost immediately, and a year later his lymphoma was gone.

Life purpose

After recovering from leukemia, during the period of his healing from lymphoma, Dean says met Bobbi -- now his wife. He says she is the miracle that shocked him more than anything.

He wrote on Instagram "Little did I know that when I made the choice to love life rather than fight cancer, that life would bring a love as precious as Bobbi."

He both credits his love with Bobbi with both being critical to his recovery, and a product of it. For Dean, healing happens on the inside and the outside at the same time.

Now he says that his prayers have been answered, and he has found his purpose.

"My purpose is to inspire others to get out of this postmodern digital cloud and reconnect with Nature," he said. "I think as we learn to connect with Nature, (then) Nature will do like it did for me and heal us in ways more than just physically.

"So my purpose is to shine a light on the power of Nature and its healing."


  • Soares CM, Teixeira AM, Sarmento H, Silva FM, Rusenhack MC, Furmann M, Nobre PR, Fachada MA, Urbano AM, Ferreira JP. Effect of exercise-conditioned human serum on the viability of human cancer cell cultures: A systematic review and meta-analysis. Exercise Immunology Review. 2021 Jan 1;27.

  • Kurgan N, Tsakiridis E, Kouvelioti R, Moore J, Klentrou P, Tsiani E. Inhibition of Human Lung Cancer Cell Proliferation and Survival by Post-Exercise Serum Is Associated with the Inhibition of Akt, mTOR, p70 S6K, and Erk1/2. Cancers (Basel). 2017 May 8;9(5):46. doi: 10.3390/cancers9050046.


About the Author

Thomas P Seager, PhD is an Associate Professor in the School of Sustainable Engineering at Arizona State University. Seager co-founded the Morozko Forge ice bath company and is an expert in the use of ice baths for building metabolic and psychological resilience. Subscribe to for more information from Seager on taking charge of your own physical & mental health.

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