Longest unsupported swim

Swedish adventurer completes world’s longest unsupported swim

Swedish adventurer Jari Cennet Tammi has successfully completed his second attempt at what is believed to be the world’s longest unsupported swim, from Stockholm to Helsinki across the Baltic Sea

It’s been a challenge two years in the making for Swedish adventurer Jari Cennet Tammi – a 500km unsupported swim from Stockholm to Helsinki across the Baltic Sea.

Jari made his first attempt at the swim in summer 2022 but had to abandon the challenge when wind changes would have caused him to miss the island of Lågskärfyr. Missing this island would have meant no other land in sight within 50km.

After months of rigorous training (including towing a Ruckraft weighted with 6kg, plus four filled 5L canisters) Jari embarked on his second attempt on 10 June 2023. His challenge involved navigating his way through Stockholm’s archipelago of over 30,000 islands, and busy shipping traffic in the Åland Sea.

The swim took him 41 days (plus 11 days waiting for the right weather conditions). He towed his own kayak containing his food and gear and swam an average of 13.9km per day. We spoke to Jari about his incredible adventure.

Jari, on your first attempt from Stockholm to Helsinki, you had to abandon the challenge because of wind changes. How were conditions this time?

This year I had a light westerly wind when I started. After 10km the wind died down and the sea became like a mirror. With the experience I had on my first attempt, I knew I’d never have managed the 33.3km crossing if that wind had continued. My Alpacka raft was far too heavy for this – more than 100kg.

What was the toughest part of the challenge?

It was when I approached Hankö. I had it in my head that I’d reach warmer water when I entered the Gulf of Finland, but this didn’t happen because there was an offshore wind for several days. The water temperature was 8 degrees when I reached Hankö, and I had 2000 meters left to the beach. I’ve never been scared during a swim before, but my fingers, toes and face were numb. I started having trouble breathing, which isn’t surprising because I’d already swum more than 12km.

One day I had all the symptoms for SIPE. I called 112 and the coastguard picked me up and took me to a waiting ambulance. They brought me to hospital for a check up but luckily all tests came back fine.

Jami’s Tracker shows routes of his 1st and 2nd attempt

When did you become confident you’d complete the swim?

About 20km from my starting point, on the Swedish side, in the Åland Sea. when I passed Flute Lighthouse I knew that I’d make it. Last year I had to abandon the swim 3-4km north of that lighthouse. The sea lay before me like a mirror, and I was only 13km away from the island I was heading to. I swam this stretch in 12h15m – a distance of 33.3 km.

How are you recovering after you challenge?

When I was swimming, I didn’t really notice how tired I was. Now I’m home, I can honestly say I’m completely exhausted. I haven’t swam since I got home but next week I’ll jump in the pool again. I still wake up at 2.30am – I haven’t got my sleep in order yet, so that’s a priority now.

If you were to do the challenge again, is there anything you would do differently?

I’d bring a more varied diet. And more sweets.

Read our interview with Jari prior to his challenge. Find out more about Jari’s challenge on his Facebook page.

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Abi writes swimming news stories and features for the Outdoor Swimmer website and manages the social media channels. She loves to swim, run, hike and SUP close to her home in Herefordshire. While she’s a keen wild swimmer, Abi is new to the world of open water events and recently completed her first open water mile. She has previously written for The Guardian, BBC Countryfile Magazine, BBC History Magazine and Ernest Journal.