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

Open water swim events for triathletes: build your swim with UltraSwim 33.3

If the swim is the leg you dread, an UltraSwim 33.3 event is the fastest way to change that. This is a focused four day open water block in warm water, with coaching and full support, that builds the endurance, sighting and pack confidence triathletes need on race day.

For triathletes

UltraSwim 33.3 #10 Montenegro, swimmer in the Bay of Kotor

Why triathletes choose UltraSwim 33.3

Most triathletes train the swim in a pool and then wonder why race day feels so different. UltraSwim 33.3 closes that gap. Four days of varied open water swimming builds the aerobic base, the sighting confidence and the pack swimming skills that transfer straight to a triathlon start, in water warm enough to focus on technique not survival. You come back with a bigger engine, calmer starts and a swim leg you look forward to rather than fear. It is the most effective swim block you can put in your triathlon year.

Many triathletes who are for the moment unable to run or ride through injury, also come to UltraSwim 33.3 to fill that void - a unique swimming challenge that will also boost their in water confidence before they return to their next triathlon season.

See our training plans

The swim leg, transformed

Four days of real open water does more for your triathlon than months in the pool. When you come to your triathlon, the swim will feel easy! As a triathlete you already have an advantage. Having the fitness required and experience of open water swimming, you're already half way there. We can help you with your training and offer free technique analysis to our ULTRA and ULTRA +/++ clients through one of our Affiliate coaches.  

How the format works

"Nothing great is easy"

Captain Matthew Webb, first to swim the English Channel, 1875

What four days builds

Six to ten kilometres a day for four days gives you more open water time in a single week than most triathletes get in a season, and an engine that carries your whole race.

Just getting to the start line is already 90% of the work. We know (because we’ve seen it first hand) that with the right preparation, anyone can become a 33.3 Finisher. And you know what, even if you don’t make finish line of every single swim, you’ll be enormously respected for what you’ve achieved, regardless. Swimming might be a ‘solo’ activity, but at our events, it is more like a team sport, with everyone helping each other out and supporting one another.

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A swim block and an adventure in one

This is not a dry training camp. It is four days in a warm water destination, swimming an iconic distance with a community of like minded athletes, staying in a luxury hotel with everything organised. You train harder than you would alone because the format and the people pull you along, and you come home with a transformed swim and the kind of experience you will talk about for years. Many triathletes return year after year, treating it as the cornerstone of their season.

Explore the experience

Skills you can use

Sighting, drafting and pacing only improve in real open water. Four warm water days give you the repetitions to make them automatic by your next race.

Sharpen your open water skills

A calm, fully supported swim

The crowded, anxious triathlon swim start is the opposite of how UltraSwim 33.3 feels. Every group swims with two safety boats and two kayaks alongside, GPS tracking and on water feeding, with a medical and physio team on site, so you can rebuild your confidence in calm, fully supported open water.

You will be fully taken care of so all you have to focus on is the swimming.  

How to book
UltraSwim 33.3 #9 Greece feed stationUltraSwim 33.3 #10 Montenegro, swimmer feeding mid swim
UltraSwim 33.3 #10 Montenegro, underwater view of a swimmer

Why triathletes keep coming back

Watch how the multi day format transforms the swim leg, from nervous starts to confident open water cruising in warm water.
As a triathlete, you are already have the endurance capability and determination that is required to swim 33.3km. You are committed to training and preparing, we can help with the rest.

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A focused swim block, all inclusive

From €1,800, your package covers four days of supported swimming, luxury hotel accommodation, breakfasts and lunches, transfers and a structured preparation programme. It is the most efficient and most enjoyable swim block in your triathlon year, with everything organised so you only have to swim.

All inclusive from €1,800. Hotel, transfers, race. Everything organised.

See prices and packages
Not sure which event fits you?

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All our events so far have won awards. See reviews from other swimmers.

Gold Award 2025 RaceCheckGold Award 2024 RaceCheckGold Award 2023 RaceCheckTop Rated 2024 RaceCheck

Common questions from triathletes

No. A clear majority of swimmers at UltraSwim 33.3 events have never swum more than 5km in a single swim before they line up at the start. The four day format spreads the 33.3km into daily swims of 7 to 9km, with a 10km marathon swim on day three when you are at your strongest. The math sounds intimidating. The format makes it possible.

When do the 2026 events run?+

Croatia 15 to 18 May. Milos Pioneer 29 May to 1 June. Switzerland 24 to 27 July. Greece (Skopelos) 18 to 21 September. Montenegro 2 to 5 October. Barcelona Compact 17 to 18 October. Nevis Caribbean Pioneer 2 to 5 December.

Is the 17 week plan enough to train for 33.3km?+

Yes, for most triathletes who already swim train three to four times a week. The programme builds your endurance progressively and takes you to 8km long swims before race week.

How much does an UltraSwim 33.3 event cost?+

All inclusive packages start from €1,800 and cover accommodation, world class safety, support and the full four day swim. A €500 deposit secures your place and is fully refundable within 30 days. Exact pricing is shown on each event page.

Can my partner come too?+

Yes. Partners are welcome whether they swim or not. Non swimming partners join the trip as part of the package, with plenty to enjoy on shore while you are in the water, and everyone back together at each finish and over dinner.

How much time off work do I need?+

Most swimmers allow around five to six days, the four day event plus travel either side. Many extend the trip to enjoy the location. Exact dates for each event are on the event pages.

ASK CAPTAIN WEBB

Questions? Captain Webb has answers

Captain Webb is your go-to guide for everything UltraSwim 33.3. Whether you’re wondering about an event, preparing for your swim, travelling to a location or simply looking for more information, Captain Webb is here to help - 24/7.
You'll find him floating in a pink bubble on the right hand side of your page.

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