Swimmers in warm open water at an UltraSwim 33.3 event in Greece

How UltraSwim 33.3 began, and where it is going

UltraSwim 33.3 was born from a simple idea: the English Channel distance is one of the most iconic numbers in sport, but is a notoriously difficult to organise and plan challenge - and not an easy piece of ocean to cross. Mark Turner founded the event in 2018 and ran the first pilot in Montenegro with just 20 swimmers - the idea being to take on the same distance, but spread over 4 days, in warmer and more hospitable waters, staying in luxury hotels and backed by a team that treats you like a pro. It has since grown into seven events across Europe and the Caribbean, with a community of more than 1000 Finishers.

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Our Journey

From a bold idea to a global swimming community

The Idea

A question that changed everything

The founding idea was simple: the English Channel distance — 33.3km — is one of the most iconic numbers in open water swimming. What if you could swim it over four days, in warm water, with world class safety and a luxury hotel, alongside hundreds of extraordinary people from all over the world? Nobody had built that event. We decided to.

The First Event

The first swimmers to become 33.3ers

The first UltraSwim 33.3 edition launched in Montenegro. A group of swimmers from across the world came together to complete the 33.3km over four days. Many arrived not knowing anyone. Every single one left with new friends for life. We knew immediately we had built something special.

Growing Community

New locations, new editions, the same extraordinary spirit

As word spread, UltraSwim 33.3 expanded to new locations, Greece, Montenegro, Switzerland, Croatia, Spain, and the Caribbean. Each edition used the same formula: iconic locations, warm water, world class safety, luxury hotels, and a community of swimmers aged 14 to 76 who proved that anything is possible.

Today

A new category of endurance sport event

UltraSwim 33.3 is now Ocean Positive certified, with events on multiple continents and a community of over 1000 33.3ers who have completed the iconic distance together. The events hit the perfect balance between challenge and achievability. You will be pushed to your limits. You will also be fully supported, every stroke of the way. Exactly as it should be.

Making the world's most iconic open water distance achievable for everyone

Our Mission

Our mission is to deliver Epic Adventure Swim Races™, with significant positive impact, for the diverse global community of open-water swimmers. Offering unique multi-day, point-to-point swim challenges, we inspire and support participants to push beyond their mental and physical boundaries for a truly transformational experience. Hosted in breathtaking locations, our events combine innovative, industry-leading safety and organisational standards with a premium travel experience. As a community owned organisation, our commitment to environmental and social responsibility reflects our core values and drives our vision to effect a positive impact on each of our stakeholders.

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If you're interested, but can't commit to a challenge right now, subscribe to our newsletter and receive an edition of Flow magazine, UltraSwim 33.3's ultimate guide to open water endurance swimming.

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How UltraSwim 33.3 began, and where it is going

From a bold idea to a global swimming community

Making the world's most iconic open water distance achievable for everyone

Join us for the adventure of your lifetime

Stay Informed