About Swim Shikoku

Swim Shikoku will be preceded by Swim Shōdoshima in July 2026. Between June and September 2026, Steven Munatones will swim entirely around Shikoku following a zigzag course the 1,200 km circular walking path of the Shikoku Pilgrimage, a Buddhist route to 88 temples on the island. He will swim around island, swimming point to point, an average of 15 km per day. This bold adventure of endurance is his example of ikigai on the 10th anniversary of his widowmaker heart attack in 2016.

How is swimming 1,188 km possible?

KAATSU Training

When her emerged from his coma with a new stent in his heart, he used KAATSU to increase the elasticity of his vascular tissue and regain the 29 lbs. of muscle he had lost. He was able to recover quickly and has used KAATSU to build his strength and stamina into his 60’s.

Ocean Experience

A native of Los Angeles, he has swum in the ocean all his life. He lived in Japan in his 20’s and completed 5 unprecedented marathon swims across Lake Biwa, across the Tsugaru Channel (both ways), and various channel crossings in Okinawa, all covered by NHK-TV.

Daily Discipline

Without fail, he wakes between 4:00 – 4:30 am to either swim in a pool or the ocean. He also walks or does KAATSU session on a daily basis. For the past 2 years, he has swum 8 km daily and will increase that daily training distance to 12 km leading up to Swim Shikoku.

A Lifetime of Experiences

He will draw upon his 50+ years of swimming in the ocean to plan, prepare, and succeed Swim Shikoku. He has coached many and helped other adventurers plan and execute their own swims. His lifelong body of cumulative knowledge and experience will be used to swim safely.

Experienced Support Crew

A successful marathon swimming adventure in the ocean is not possible with an experienced support team. Chris Morgan, an Olympic coach, Chief Performance Officer of KAATSU Global, and one of the world’s preeminent escort kayakers of history’s longest swims, will head the support team.

Positive Mindset
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The moment that he woke from the coma and was told by his doctor that he had a heart attack, his first thoughts were that “this could not happen to me – but if it did, I get a second chance at life and want to make the most of the rest of my life.” The concept of “ikigai” – having a reason for being and a sense of purpose drives him.

The Crew

Event Coordinator

Yuko Matsuzaki

Matsuzaki-san is Japan’s only athlete inducted as an Honor Swimmer in the International Marathon Swimming Hall of Fame and was Japan’s first professional swimmer.

More about Yuko

Biography

A graduate of Tsukuba University and a native of Tokyo, Matsuzaki-san was a professional marathon swimmer from 1989 to 2003.  She competed in professional marathon swims between 22 and 89 kilometers in lakes, rivers, seas, and oceans in Italy, Greece, Bermuda, Argentina, USA, Canada, Serbia, France, and Brazil.  She was one of the most prolific marathon swimmers of her generation and was inducted as an Honor Swimmer in the International Marathon Swimming Hall of Fame in its Class of 2011.  She accepted the Honor at the United Nations in New York City in October 2011.

In 2014, she was officially recognized as a professional marathon swimmer by the United States of America’s federal government and she was named to the World’s 50 Most Adventurous Open Water Swimming Women by the World Open Water Swimming Association in 2015.  

Media  

  • She wrote a book called Marathon Swimming: My Fun Journey.
  • She wrote for SWIM Magazine and JOYO newspaper every month.
  • In 2002, she appeared in the TBS documentary program Jonetsu Tairiku (「情熱大陸」) in Japan which interviews and introduces people who are active in various fields with the program Marathon Swimmer, Yuko Matsuzaki (「職業：マラソンスイミング」). The program won the Galaxy Award Monthly Award.
  • She served as a photographer in the America, Florida, Orlando editions of the travel guidebook Travelling Around the World.

Family

Her father, Yamato Matsuzaki, joined the Japan Coast Guard in 1953 and served in various roles, including as an education officer and head of the 9th Regional Headquarters, before retiring in 1984 as the Chief Inspector of the Japan Coast Guard. He later served as chairman and advisor of the Japan Coast Guard Association. In 1997, he was awarded the Order of the Third Class.

Solo Swimming Career Highlights

Professional Marathon Swimming Career Highlights

Matsuzaki’s international career includes a number of professional marathon swims:

  • in Bermuda
    • In 2007, she completed the 10 km Bermuda Round-the-Sound in Harrington Sound in 2 hours 39 minutes at the age of 44.
  • in Brazil
    • On 5 February 1995, she competed in the 26 km Tapes Marathon, finishing in 9 hours 1 minutes.
    • She completed in the 26 km Tapes Marathon, finishing in 7 hours 40 minutes.
    • She completed in the 26 km Tapes Marathon, finishing in 8 hours 30 minutes.
  • in France
    • She completed the 25 km Le Flow Gabarriers.

Rules of Engagement

A stage swim is a solo swim conducted over two or more consecutive days where the exact distance of the individual stages can vary depending each day. The starting point of the subsequent stages begins at or behind the same point as the finish of the previous day’s swim. A swim must take place on every day during the swim duration. There are different types of stage swims due to safety, logistics, circumstances, or conditions.
Munatones will swim in a counterclockwise direction around Shikoku. They will attempt to swim point-to-point along the Shikoku coastline, but this is not geographically possible due to islets, gill nets, and marine pens along the rugged coast in the 17°C – 24°C water between June and September 2026.
The goal is to swim entirely around Shikoku, one day at a time. When the conditions become unswimmable due to Pacific Ocean storms and typhoons, he may not be able to enter the water, let alone go outdoors. In these inevitable cases, the non-swim day will be documented.
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Swim Shikoku starts on 17 June 2026 with an anticipated finish on 12 September. If he does not complete the swim within 88 days, the swim is deemed a DNF (Did Not Finish). Each day and each swim will be videotaped, photographed, and document in writing. The start and finish locations and time, total time and distance swum, the water ad air temperature and conditions will be recorded. The next day, he will begin his next swim segment at the same location where he stopped the day before. 
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The schedule plans on 70 swimmable days and 18 unswimmable days due to anticipated storms during the typhoon season in August and September. The start times of the swim stages will be dependent on the tidal flows and winds.

There are numerous aquaculture zones, fishing hazards, and other marine risks that will be encountered during the swim. In addition to the fishing infrastructure that must be avoided, there are set fishing nets (fixed and floating) extending up to 300 meters from shore, floating seaweed and kelp rafts anchored offshore, stake nets (yanagi-ami) in shallow tidal flats, underwater mooring lines and ropes from aquaculture platforms.

The swim will be a very difficult physical and mental challenge where the equipment will include a normal porous swimsuit, swim cap, ear plugs, goggles, and possibly a swim snorkel if the skin of his mouth, tongue, and inner lining of his throat are impacted due to the high salinity of the water. 

He will use zinc oxide to provide sun protection, use KAATSU equipment twice daily for warm-up and recovery, and wear a Garmin smartwatch. He will use an iPhone, a MacBook Pro laptop, and a GoPro cam. The Kuroshio Current has a strong influence along southern coast that will either assist or oppose the progress of the swim. The tidal flows are particularly strong near the Naruto Strait and the Seto Inland Sea. The typhoon seas peaks in the summer, especially during August and September when downtime and weather delays will be a forced part of the swim. The Pacific Ocean side of Shikoku has high swells and strong winds while the Seto Inland Sea is calmer with more navigable waters.
 
His support team will carry a line cutter and safety blade in case of entanglement in the marine infrastructure or nets.

What Will Be Difficult About Swim Shikoku?

Weather

Swim Shikoku will take place between June and September. August and September is typhoon season in Japan where the ocean becomes absolutely unswimmable for days at a time. 18 unswimmable days are calculated into the overall plan.

Physical + Psychological Demands

His ability to recover from continuous hard days of swimming after weeks and months will gradually become less. The second half of Swim Shikoku will be excruciatingly difficult, both physiologically and psychologically.

Ocean Environment

Point-to-point straight-line tangents are impossible due to numerous aquaculture zones, fishing hazards, and marine infrastructure that must be avoided, including fixed and floating fishing nets extending up to 300 meters from shore, floating seaweed and kelp rafts anchored offshore, nets (yanagi-ami) in shallow tidal flats, underwater mooring lines and ropes from aquaculture platforms, industrial port debris and waste runoff near urban zones, plankton blooms, and early morning fog

Health of Support Crew

The logistics of traveling from point to point, from location to location, from hotel to hotel, will be exhausting for both swimmer and the support team. They must be understanding and appreciative of each other’s efforts and fatigue.