# Researchers compared 1,200 outdoor swims across 19 countries and found wild water produced a stronger wellbeing boost than open-air pools, largely because natural settings supported autonomy and competence

> A study of 1,200 outdoor swims across 19 countries found that time in wild swimming locations such as lakes, rivers and the sea was linked to a stronger boost in positive wellbeing than sessions in open-air pools. Both settings were associated with...

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Published: 2026-08-06T19:40:02+00:00
Categories: Explainer, Humans

![A woman swimming in a quiet lake surrounded by green vegetation](https://www.argo.net/wp-content/uploads/2026/08/wild_swimming_lake_person.jpg)

A study of **1,200 outdoor swims** across **19 countries** found that time in **wild swimming** locations such as lakes, rivers and the sea was linked to a stronger boost in positive wellbeing than sessions in **open-air pools**. Both settings were associated with better mood and lower stress, yet the natural sites produced a clearer extra lift.

The paper, published in the [**Journal of Environmental Psychology**](https://doi.org/10.1016/j.jenvp.2025.102558), asked a practical question. If people already benefit from swimming outdoors, does the setting itself add something meaningful when the water is no longer contained by pool walls, lane ropes and fixed edges?

The answer centered on **self-determination theory**. The researchers found that feelings of **autonomy** and **competence** helped explain why open water felt better for many swimmers. Social connection still had value, but it accounted for much less of the gap than many enthusiasts might expect when they describe the appeal of group dips and club culture.

## The study compared swims, not swimmer identities

The research team did not simply ask whether people liked wild swimming. It used recalled visits from a large international sample and compared how participants felt after particular swimming sessions. That matters because the paper focused on the immediate experience of a swim rather than a broad life story about whether a person thinks of themselves as adventurous, athletic, social or health conscious.

The international reach was important. Earlier work on wild swimming often came from small groups in one region, which made it hard to know whether the same pattern would hold in other climates and cultures. The 19-country design let the authors test whether the mental-health advantage of open water still appeared once the sample grew much larger and much more diverse.

A useful summary from the [University of Washington Nature and Health](https://natureandhealth.uw.edu/publications/the-psychological-benefits-of-open-water-wild-swimming-exploring-a-self-determination-approach-using-a-19-country-sample/) project makes the comparison plain. Participants reported on outdoor swims in natural water and on swims in outdoor pools, which gave the study a cleaner way to separate the value of being outside from the value of being in a less controlled environment.

## Wild water produced the stronger wellbeing lift

The headline result was straightforward. Swimming in both settings was associated with high positive wellbeing and low negative wellbeing, yet open water came out ahead on positive wellbeing. The study therefore supports a more specific claim than the broad idea that swimming is good for people. The location appears to matter.

The authors did not present open water as magic. Instead, the pattern suggests that natural settings can change how effort, movement and attention are felt during a swim. A shoreline, current, changing temperature or the sight of open distance may alter the experience enough that the same physical activity carries a different psychological reward.

**James Grellier** of the University of Exeter described that mechanism clearly in a university release: "Open-water swimmers reported feeling a greater sense of independence and mastery over their environment." That short line helps explain why the advantage showed up in the data without requiring exaggerated claims about instant transformation or universal benefit for every swimmer.

The [University of Exeter report](https://news.exeter.ac.uk/faculty-of-health-and-life-sciences/wild-swimming-boosts-mental-health-more-than-open-air-pools/) also notes that both forms of outdoor swimming reduced stress and improved mood. Open water therefore did not replace the value of pools. It added another layer that many swimmers appear to register as freedom, challenge and direct engagement with a changing setting.

## Autonomy and competence explained most of the gap

The mediation analysis pointed to two forces above all. People in natural water more often felt free to choose how they moved, where they entered, how far they went and how they responded to conditions. Those are classic markers of **autonomy**. They also more often felt capable of meeting the demands of the setting, which maps onto **competence**.

Those two ideas can sound abstract until they are attached to a swim. A pool usually tells the swimmer almost everything in advance. The dimensions are fixed, the entry is obvious, the depth is marked and the route repeats. A river, lake cove or sea inlet asks for more judgment. Swimmers read the water, gauge their comfort, adjust pace and make small decisions throughout the session.

The study suggests that these added decisions can heighten the sense of agency when the swimmer feels ready for them. That may be why natural water produced a larger lift in positive wellbeing. The gain did not depend mainly on being with other people, even though companionship often helps people feel safer and more willing to enter open water in the first place.

An [overview from BlueHealth2020](https://bluehealth2020.eu/publications/mental-health-boost-wild-swimming-open-waters-make-difference/) frames the finding in similar terms, linking the open-water advantage to freedom and challenge rather than to scenery alone. The paper therefore adds a useful psychological mechanism to a public conversation that is often dominated by anecdotes, cold-water bravado or romantic imagery.

## Anxiety did not disappear and skill could cut both ways

The study did not suggest that every part of wild swimming feels calm. One of its most interesting findings involved anxiety, where the pattern was more complicated. The authors proposed that more competent swimmers may choose locations that are less safe or more demanding, which could raise anxiety even while the overall experience still feels meaningful and rewarding.

That nuance is important because it keeps the paper grounded in real behavior. A swimmer who feels strong enough to enter deeper water, rougher surf or a colder quarry may experience a sharper sense of achievement, while also carrying a more serious awareness of risk. Positive wellbeing and situational tension can therefore exist within the same outing.

Lead author **Wencke Groeneveld** emphasized access and safety in the public discussion of the results: "Ensuring safe access to high-quality open-water locations could help more people enjoy the benefits." The wording matters because the paper does not argue for careless exposure. It argues for conditions that let more people experience autonomy and competence without unnecessary danger.

A related publication record from the [University of Edinburgh](https://www.research.ed.ac.uk/en/publications/the-psychological-benefits-of-open-water-wild-swimming-exploring-/) preserves the same abstract language about more anxiety in some settings and ties the result back to the broader evidence base. The finding therefore reads as a limitation and a planning cue, not as a contradiction.

## Safe access may be the part with the biggest public-health value

The study matters beyond individual preference because it points toward design choices. If natural water can produce a stronger wellbeing lift than outdoor pools, then access to swimmable coasts, lakes and rivers becomes more than an amenity issue. It starts to look like a public-health question that touches water quality, entry points, safety information and local maintenance.

The data came from the **BlueHealth International Survey**, a European Union backed effort that tracked how people use blue spaces and how those visits relate to health and wellbeing. That broader context helps explain why the authors treated swimming as one part of a wider relationship between people and water, rather than as a niche hobby for dedicated cold-water communities.

For readers who do not swim in the wild, the paper still offers a clear message. Controlled settings support health and natural settings may add a further mental benefit when swimmers feel prepared for them. The strongest part of the evidence is therefore neither romance nor fear. It is the simple idea that environments which support agency and mastery can change how exercise feels in the mind.