As exams (for most) wrap up, many students flock to Grantchester Meadows or Jesus Lido for a dip in the water as it begins to heat up after Spring. For some, however, cold-water swimming is a year-round pastime, with many braving the icy waters in Michaelmas and Lent.

The benefits of cold-water swimming are well-documented. Aside from the physical exercise, studies have shown links with lower anxiety, reduced blood pressure, and increased dopamine levels. With a rise in cold-water swimming across the country and Cambridge’s easy access to water, it is no wonder that some in Cambridge are taking the plunge.

One such group is the aptly named Serotonin Swim. Set up by Sam Thorogood, the group meets at the unheated and outdoor Jesus Green Lido every Sunday between October and May. At 100 yards (91 metres) in length, the Jesus Green Lido is one of the longest pools in Europe and in the depths of winter, this can seem a dauntingly far distance. As such, to entice people into swimming one length (or more if they wish), participants receive a mini reward, such as a sticker or sweet.

Talking to Sam, it is clear that the mental health benefits of swimming are the main drive for many of the group, which comprises students, academics, and townies in equal measure. “When you go for a swim, especially if it’s colder water swimming, you can’t think about anything else, so you’re immediately present,” Sam explains. “That allows you to just not worry about the past or the future. You’re just present, and things feel more okay."

“studies have shown links with lower anxiety, reduced blood pressure, and increased dopamine levels”

For students who prefer a plunge on the wilder side, the newly created Cambridge Cold Water Swimming Society (CCWSS) takes trips to Grantchester Meadows every Tuesday morning, with the intrepid swimmers rewarded with hot chocolate and chocolate brioches post-plunge.

Its co-founder, Aron Walters, a 2nd year NatSci, said that his decision to start the group came from a history of river swimming in Dorset, and, after a trip to Grantchester in first year, he decided to bring that love of nature to Cambridge. As a busy student, the calming benefits of the river are crucial for Aron: “My week is quite monotonous with work and things like that. Just having like a morning a week to take myself completely outside of that by going swimming with friends – it’s something that’s completely different to everything else in my routine.”

For many of the swimmers of CCWSS, it is the frosty winter months where the benefits of wild swimming are really felt. “In the colder months there is definitely a buzz that I get from it as well […] it kind of like alters my state of mind,” Aron explains. “No matter what else has been going on, whenever I am in the water, especially that cold water, it goes away from me a little bit.”

For Aron, as well as Sam, it is not just the chemical benefits of swimming that bring them back to the water, the social element is also a draw. “When you share a love of swimming, you share a love of taking that moment out of your day and just doing something for you to help you cope and recover,” says Sam. For Aron, part of his passion is about “creating a space where people would just get together in the morning, outside in nature, and enjoy the swimming”.

“We’re wild water beings, really.”

However, swimming in the Cam is not without its risks. Aside from the standard dangers of swimming, pollution is well-documented. In 2024, a stretch of the river at Sheep’s Green was awarded Bathing Water Designation. With this status comes mandatory testing for pollution and testing has shown consistently poor water quality with high levels of E. coli and phosphate levels three times the upper limit defined by the Water Framework Directive. With multiple wild swimmers having fallen ill following swims, CCWSS is careful to remind people of the dangers. The society keeps an eye on the forecast for any heavy rainfall in the days leading up to a swim, and they advise that no-one put their head underwater.

Tony Booth, co-founder of citizen climate group Friends of the Cam and current candidate for University Chancellor, lays blame for this river pollution at the feet of Anglian Water and the University. “The water companies are criminal organisations,” he said, and “it’s in their interest to pollute the river”. “The iconic river in this city goes right through the University, University colleges. And there should be this incredible eagerness to care for the river, but there isn’t,” he continued.

Though he has since given up swimming in the Cam, he remains an avid supporter of wild swimming and holds hope for the future of the river. “I’d advise students to get the University to put its weight behind a campaign, given the history of the River, of the River Cam, and the proximity of the Cam and the University. As he puts it, “we’re wild water beings, really. I mean we are water, 65% of our bodies are water, so it’s a natural environment for us.”

For the near future, at least, it seems as though the levels of both swimmers and E.Coli will remain high in the Cam. For those that want to bask in the benefits of cold-water swimming this summer and beyond: do your research, stay safe, and, if you choose the Cam, keep your head up!