In Vienna, on a Wednesday in July, around half past six in the evening, the Alte Donau fills up with people fresh out of the office. Nothing organised about it: they undress on a towel, get in, swim for half an hour, go home. Across Europe this summer, the same scene repeats itself on thousands of lakes, rivers and stretches of coast. It has a name — wild swimming — and behind it there is more than fashion: there is hard data on water quality that makes it possible.
A trend born in Britain, grown across the continent
Swimming outdoors for pleasure, not competitive training, took off in the UK starting in the early 2020s — helped along by the pandemic, which pushed many people to rediscover the rivers and lakes near home while pools and gyms were shut. From there the habit spread to the continent, tangling itself up with a bigger movement: outdoor wellness travel, which operators are naming among the defining trends of the 2026 European summer.
It isn't only a passing fashion. Swimming in a lake or the open sea, with no lanes and no edge within reach, changes your relationship with the sport: it adds navigation, breath control in moving water, reading the conditions. It's a different experience from pool swimming, not necessarily harder, but with its own rules.
The water is cleaner than you think — and the numbers back it up
The most common fear about open water swimming is water quality. Here the data helps put the problem in perspective. According to the European Environment Agency's 2025 report on inland bathing waters, Austria has the highest share of sites rated excellent: 96.5%. Finland follows (94.7%, across more than 187,000 lakes), then Germany (91.5%) and Italy at 87.7% — above the continental average. Further down the list sit France (71%), the Netherlands (70.4%), Hungary (64%) and Poland (56.7%).
The gap between countries is real, but the underlying picture is a good one: most monitored bathing sites in Europe are rated good or excellent. Swimming in open water today isn't the hygiene gamble it might have looked like twenty years ago — it's a regulated, monitored activity that, in the vast majority of cases, is safe from a water quality standpoint.
- Attersee, Austria — alpine water with visibility up to 7-9 metres in summer, among the clearest lakes on the continent
- Lake Tuusula, Finland — summer temperatures of 18-22°C, one of 187,000 Finnish lakes larger than 500 square metres
- Lake Hévíz, Hungary— the world's largest swimmable thermal lake, 22-36°C year-round
- Lake Kaltern, Italy — up to 28°C in summer, among the warmest alpine lakes in Europe
The rule no experienced swimmer ignores
That said, water quality isn't the only risk. A pool has an edge every twenty-five metres and a lifeguard on duty. A lake or the sea changes the geometry entirely: the shore can be far away, currents — even the ones you can't see on the surface — can move you dozens of metres in a few minutes, and a cramp you can't shake off needs real help, not just a pause.
That's why the number one rule of every open water swimming federation is simple and non-negotiable: never swim alone. You don't need a personal lifeguard — just one other person who can swim, who can see you, who knows where you are. It's the cheapest, most effective safety measure there is, and yet the one most often skipped, often because finding someone with the same pace, the same comfort level in open water and the same free time isn't always easy.
On PlaySportMateyou can search by sport, city and level, and it's built with exactly this in mind: finding people who swim near you, pool or open water, instead of relying on an old post in a Facebook group. If you want to keep the same group for recurring outings — the same Saturday dawn swim at the lake — you can organise it in a Crew.
A different way to spend the summer
There's something almost meditative about open water swimming: your head underwater, the noise of the world disappearing, just breath and stroke. But it's also, in a way rarely mentioned, a social sport — what happens afterwards, sitting on the shore comparing notes on that odd current halfway through, matters almost as much as the swim itself.
If this piqued your curiosity, take a look at how swimming plays out at the 2026 European Championships between the Olympic pool and the Seine. And if you'd rather stay on land, the same logic for finding a partner applies to summer running.
Frequently asked questions
Which European lakes have the cleanest water?
According to 2025 European Environment Agency data on inland bathing waters, Austria leads with 96.5% of sites rated excellent, followed by Finland (94.7%) and Germany (91.5%). Italy sits at 87.7%, above the continental average.
How is bathing water quality measured in Europe?
Every EU member state periodically monitors its bathing sites — sea, lakes, rivers — under the EU Bathing Water Directive, which rates each site as excellent, good, sufficient or poor based on bacterial levels. The data feeds into the European Environment Agency's annual report.
Is it safe to swim in an alpine lake or a river?
It depends on the specific site, not the country as a whole: even areas with excellent average quality have spots best avoided after heavy rain or near tributaries. The practical rule is to check local signage and, where available, official bulletins before getting in.
Why did wild swimming become a trend in 2026?
The momentum started in the UK, where river and lake swimming grew fast from the early 2020s, and spread across Europe alongside the wider outdoor wellness travel movement. The real, documented improvement in water quality made the experience more accessible and less risky than it used to be.