Join swimmers from all over the globe to celebrate your longest swim


Get your atlases out as the Longest Swim on The Longest Day club has become seriously international: hundreds of swimmers have joined our event from around the globe. Queenstown, Melbourne, Singapore, Yellowknife, Vancouver…  Alberta, Seattle, Washington State, California, Maine, Massachusetts, Newark and Milwaukee, Edegem, Braunschweig, Hanover, The Netherlands, Norway, Valencia, Dublin, France and the four nations of the UK. 

June 21 may be your longest day or it may be your shortest. If you live somewhere near the equator your days and nights will be more balanced. You have told us that to qualify for the longest swim all that matters is a passion for open water and a desire to swim together – we will be swimming apart, around the world, yet observing together our longest swims.

Join us to celebrate! Any age, any distance, any place. We will be sharing training tips, planning tips and a Logbook of Longest Swims from around the world.

This is a fundraiser for The Outdoor Swimming Society and Project Seagrass. One supporting peoples’ swimming dreams; the other helping preserve our watery planet.

Solstices are moments of transition, turning points. There are contrasts: long and short; day and night; light and darkness; cold and warmth. And a steadying calmness, as the natural cycles take place in their measured, unhurried way.  

They are times of celebration. Right now, the spring sap is rising. Nights are drawing out, light is intensifying. Swims come with new companions: buds and birdsong. And as for the humans? You can feel the sap rising in us too, after so long locked down: that intense need to do something, to reclaim fitness and form, to have a big day out.

We can’t get together in a mass event this year, so instead we’re going to swim virtually on (or around) Monday June 21st 2021.


The swim itself can be anything you want it to be: an endurance feat in your local open water lake*, a downstream river swim, a sea swim, a crossing, a swim safari (multiple dips on the one day). It can be 500m or 10k; breaststroke or butterfly. It can be more about the hike. For more ideas, see the plans of the OSS team below.

The key is to take some time off for your swimming, celebrate the start of summer and share it with others. Whatever distance you decide to do, please make sure it is a challenge you are able to safely complete. If you are pushing yourself, have safety cover – by (for example) doing the swim at a lido, outdoor pool or lifeguarded lake.

*(see our list to find your local lake, and consider getting membership soon as we anticipate a busy summer).

Need to get in some training before the swim? Then have a look at our Couch to 5k plan, which finishes on the Longest Day.

How do I take part?

Enter the event by choosing the number of adult and child tickets you would like (there’s a £0 option for anyone broke). We will send you a welcome email and between now and midsummer, we will keep in touch with some supportive emails to keep you on-track for your swim. All paid entrants also receive a Longest Swim embroidered patch, and thanks for supporting The OSS and Project Seagrass. On (or around) June 21st 2021, complete your chosen swim and share the images and story #longestswim #outdoorswimmingsociety @ProjectSeagrass.

The Longest Swim Logbook

Curious about everyone else’s swim all around the world? Participants are invited to log their swims within the Longest Swim Logbook, a private document that will hold your name (as provided) time, place, distance, amount (if you’re going for a multi-dip, rather than a long swim). You don’t have to submit a formal record of your swim, such as an exact time or a GPS log.


Grab some friends and head to the beach #longestswim (Photo: Vladimir Kudinov)
Spend the day at the river or pool #longestswim (Photo: Kate Rew)
Do a distance challenge at your local open water lake? #longestswim (Photo: David Anderson)
Find somewhere new #longestswim (Photo: Scott Osborn)


Entry costs £15 for adults (18+), £2.50 for children (under 18) and £0 if you are broke. This is a fundraiser for The Outdoor Swimming Society and Project Seagrass, who will receive 10% of the ticket price (excl. VAT and bank charges).

Adult ticket holders will receive:

  • Longest Swim embroidered patch
  • dedicated emails to boost your planning
  • an invitation to join the Longest Swim Facebook Group
  • access to the Longest Swim Logbook, for event participants only, where you can find out what other swimmers did all over the world
  • 10% off the new OSS Eco Tow Float
  • maybe some discounts from event sponsor Red Original
  • thanks for their donation to The Outdoor Swimming Society and Project Seagrass.

Free swimmers will receive all of the above except the embroidered patch. They are warmly invited to make any donation they can to the Society.

We plan to start the longest weekend with a Saturday breakfast live online event briefing from our hit regular hosts, Paul and Llyr (and not in a swim pen).

Child swimmers will receive a free patch and access to the Longest Swim Logbook.

Stay safe in the water

Please remember that open water swimming comes with risks, which include cold shock, hypothermia, infection from polluted water, drowning and death. All swimmers are entirely responsible for themselves on any chosen swim – see the OSS Swim Responsibility Statement and you must ensure that you are capable of completing your chosen swim (or getting out!). For help and guidance on all sorts of aspects of open water swimming, please visit the Survive section of this website. Some articles you might find useful include:


Ideas for the day

Kate Rew
Al Humphries
Calum Maclean
Any distance - from a short river crossing to 50k #longestswim (Photo: Al Humphries)
big River swim team The Big River Swim Team, California
Vicki_Watson Vicki Watson is planning 3 x 5k in 3 days
day-dipper-holding Hoping for a warm family river swim at the end of the school day. Kate Rew


I am planning my favourite kind of swim: a long downstream river swim, on the Avon with friends, ending at Warleigh Wier (Somerset, England). It’s a beautiful freshwater swim, between meadows, under an aqueduct, past oak trees and rope-swings. The ultimate distance depends on how warm the water is by then and how long we can last – but I’m really looking forward to getting fit again, it’s been too long without swimming! After school I’m going to take my boys (8 and 9) to Farleigh Hungerford Swimming Club, where there’s a choice of distances depending on which rope swing they opt to start on.


Every year I look forward to June 21st –the summer solstice, the longest day– and I try to celebrate it in nature. This year the date has the added frisson of being the [hopeful] end of lockdown. I will savour this swim even more than I usually do! When I dream about a long summer swim my thoughts are of freedom: a long, hot hike through the countryside, solitude, hours of free time, and the reward of a refreshing, restorative swim when I arrive. I am not a good swimmer at all. I’m not interested in training to swim for miles. So I hope that my longest swim on the longest day will revolve around a long day in the outdoors, a long, lazy wallow in a summer river (bonus points if there are options to jump in from on high), and then a long lie down in the shade of a sunny oak tree.

  • Al loves midsummer so much he wrote a book about it – My Midsummer Morning (rediscovering a life of adventure). Perfect to inspire a summer restart


For the longest day I plan a sunrise to sunset journey – from sea, to summit…! Starting at the coast, I will make my way by foot and water to what I think is the highest swim possible in Scotland (and the UK)! An initial plan to swim every hour on the hour was soon scuppered as I remembered how dull I can find such prescriptive plans! Much better a start, and a finish and a rough idea of how to fill the middle…


The Big River Swim Team spontaneously arose last spring after the onset of the pandemic. About two dozen of us managed to find each other on the bank of our local estuary, Big River in Northern California, wondering if we could swim in it. None of us really knew each other well, but the bond of water and swimming soon formed friendships. We are between 30s-70s, some are accomplished swimmers while others are self-taught.

 None of us had swum in a wetsuit before 2020, but by July we were all buying wetsuits and comparing notes. All the while we were learning the nuances of tides, river flow, navigating around boats and curious seals. We discovered OSS online and soon were sharing articles on cold water swimming. By this fall we were all fully addicted and now we are marvelling at the fact that we have been swimming for a year. The idea of joining with OSS for The Longest Swim on the Longest Day was met with much enthusiasm. What this will look like for us will be a variety of swims based on our stamina, but everyone is going to try to make it a personal best. Some of us are aiming on a two hours swim to Seal Island, others at shorter swims – the Fuzzy Tree, or The Quarry.  


I had planned to swim butterfly for 70mins to celebrate my 70th Birthday, and it is not all down to the pandemic, that my birthday came and went! It is a long time to swim butterfly, even slowed down, going with the flow and the glide, and trying to be gentle. I have to say I was improving and feeling so pleased that I was getting more distance, and as a bonus found I could swim individual medleys in the pool, and not feel completely wrecked. So my plan is to start again, and on the longest day I will see how long I can swim butterfly. As there are only my own rules to follow, I shall take rests when I need to, and cheat where I can.


I had planned to do the triple 5km in a pool last year. When I heard about the Longest Swim weekend, I thought l would like to have a go at the triple 5km outdoors instead! For my first swim I plan to swim in Colwick Lake, Nottingham, and I’ll swim in the River Trent for my second. My third swim location will be free choice – depending on the weather and what I fancy doing at the time. I swim all year round outdoors and do my training in pools. As a black swimmer I have found open water swimming inclusive of all, regardless of age, race, gender or size. When swimming outdoors I like to immerse myself in everything around me, so these three swims will be at a leisurely pace with a 20 minute refuel (a bread roll filled with cheesy triangles). I often do long swims in relays with other women, so this will be my longest solo swim, three times.


I live with my family on an island called Flekkerøy in southern Norway. This winter, my 11 year-old son, Ib, has started swimming with me.  Initially it was just to earn extra time on his computer but, by the third time, he started really enjoying the swim for its own sake.  As the temperature water plummeted and ice formed on the sea, he became very excited with each new temperature low (we got down to 0.3˚C!). A few weeks ago, Ib asked if, during the summer, he could swim with me round one of the small islands we can see from the shore. This 400m swim will be Ib’s longest and the longest distance we have swum together. We’re both as excited as each other at the prospect of sharing this mini-adventure as part of The Longest Swim on The Longest Day.

The event is kindly supported by:




The Longest Swim on The Longest Day is a fundraising event for The Outdoor Swimming Society.

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10% of the money raised will go to Project Seagrass, an environmental charity devoted to the conservation of seagrass ecosystems around the globe.

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