We were greeted with unbridled enthusiasm by Steve, the owner of this 50-acre lake. Open-water swimming takes place throughout the year and, when we visited in August, five lifeguards were on duty.

Kids join a swim lesson at Wild Rivers for the World’s Largest Swimming Lesson, a global initiative meant to combat childhood drowning.

It started with a cold-water plunge, and now outdoor, natural swimming is an obsession of mine. With 15,000 lakes and a robust water-quality testing system, Wisconsin is great for wild swimming.

Our recent study, published in the Journal of Environmental Psychology, outlines the mental wellbeing benefits of wild swimming, and suggests that satisfying psychological needs might underlie this.