The Format
Every event has a similar shape. Four days of point-to-point swims which build to a total of the iconic English Channel distance of 33.3km in warm, crystal clear waters. Afternoons to rest, recover and explore. World class safety and premium support, so all you have to think about is the swimming.
See our eventsAward winning, all inclusive packages from €1,800
33.3km across four days. You swim one or two supported stages each morning, the rest of the day is yours. By keeping the swims spread out and the afternoons free, the 33.3km total becomes something you build towards rather than survive.
We start day one with two swims, giving you a chance to refuel and get to know your fellow swimmers. We build up to one longer distance on day two, with the marathon day on day three. By day four, you have broken the back of the distance and can relax and enjoy the final swim of your 33.3 journey.
The full 33.3km, the shortest English Channel line, spread across six or seven point to point swims over four days. Timed with rankings, though most swimmers come just to finish rather than to win.
The Half Channel. Around 17km over the same four day weekend, with no single swim longer than 5km. A non competitive format with its own Finisher droplet, and usually limited to ten places per event.
The ULTIMATE option is the full distance in one swim, a great stepping stone towards the English Channel for some. Available at just one of our events each year (Switzerland in 2027 with a double lake crossing)
Nine short questions, about two minutes of your time. We read your submission, then share information with you to help you select the right event for you.
Explore the format, structure and key elements of the UltraSwim 33.3 experience, helping you understand what to expect and how the event comes together.
This video brings the format, structure and key elements of the experience to life, showing how each stage comes together to create the unique UltraSwim 33.3 challenge. Designed to give you a feel for the event and how it unfolds, the video focuses on the experience itself - from the format and flow through to the practical details of taking part. While the video shows the practical side of how an UltraSwim 33.3 works, for a deeper feel of the atmosphere, emotion and personal stories that make UltraSwim 33.3 so special, explore our other videos.
Each morning brings a new swim. Here is how the four stages build to the full 33.3km.
Day one · two swims . 8 to 9km total
Find your flow
We usually start off with two swims on day one which is the perfect way to start your 33.3 journey. We break the distance into two manageable steps, giving you time for brief refuel in between. It is also your chance to settle into the experience, calm your pre-event nerves, adjust to the water conditions and find your tribe in the water
Day two · around 8km
Build the single swim distance
By day two, the distance steps up. You'll feel a little tired and sore from the first day perhaps. 'Over-compensation' will hold you back as your brain asks what are you doing to yourself?! After day one, you will know more about how your body will react, your energy and how to cope with the conditions. You will have in your mind that day 3 is the marathon stage - but you'll push on through and build confidence that you can do this
Day three · MARATHON DAY . 10KM
The marathon swim
Your brain finally gets it - you're not stopping yet - once you are in the water you feel stronger, mentally and physically, than ever before - even if a little sore! This is the moment where 33.3 becomes real. It's a true test of endurance but you won't be starting from zero. This is what you have prepared your mind and body for. For many it will be your longest ever swim. But you will be smiling on that finish line.
Day four · 5 to 6km
Cross the line
After the marathon, you will feel like you can do anything! Day four brings the distance back down giving you space to recover from day three while enjoying the final swim of your 33.3. This swim is about soaking it all in, the atmosphere, the amazing people and the incredible achievement of making it this far. Enjoy the final kilometres, you've earned them.
Sea temperatures across the series generally sit between 20 and 26 degrees, so cold is rarely the limiting factor. Wetsuit and skins categories are both offered. The cut off pace defaults to two kilometres an hour and is eased when conditions demand, because our aim is to get as many of you to the finish as we possibly can.
Every swimmer carries a live tracker. Our SwimTelligence system follows your position stage by stage so friends and family can watch from shore while the crew keeps watch on the water. It is world class safety made quietly invisible, leaving you free to concentrate on the swim in front of you.
Take a look at our graph of average swim speeds across a few of our events. Filter by event and category.
Source: Race timing data • Svetlana Zadedyurina @datasveta
February 2025
The format is built to be reassuring once you understand it. Most questions are about a typical day, what to wear, and what happens if a stage goes badly. Here are the answers, straight, so you can picture your week before you arrive.
Yes. Wetsuits are welcome and a lot of swimmers wear one. Wetsuit and skins compete in different categories. Both are welcome.
That's completely fine, there is no shame in that. We will get you out of the water, keep you warm and look after you, whatever you need. You can always get in and try again the next day.
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.
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.
Nothing great is easy. Choose your event and secure your spot with a fully refundable €500 deposit. Your adventure of a lifetime starts here.
Book Now