An hour south of Bern, in the Bernese Oberland, Lake Brienz does something rare: it outshines the mountains around it. Known as Switzerland's cleanest lake, its striking turquoise water is glacial-fed and stays chilly year-round — rarely climbing above 68°F — which is exactly the point for cold-plunge fans and swimmers who like their water crisp.
The lake's pristine status wasn't always a given. Back in the 1980s, poorly treated wastewater loaded with detergents and organic waste nearly wrecked the ecosystem, sending phosphorus levels crashing and fish stocks with them. Modernised treatment plants and adjustments to water flows from its tributaries turned things around, and the lake is now held up as a model of restoration. For travellers, that means water you can actually swim in — with four lidos dotted around the shore like compass points: Bönigen in the west, Brienz in the east, Niederried to the north, and Iseltwald to the south.
Getting on the water is half the experience. Paddle-steamers have been connecting the lakeside villages for generations, and today 11 boats serve nine stops on a three-hour round trip between Interlaken and Brienz. The star of the fleet is the Lötschberg, a Belle-Epoque three-deck saloon steamer with serious nostalgic charm. Between April and October you can pair the scenery with a meal on a breakfast or brunch cruise.
On land, the headline hike is the Three Waterfalls Trail, an 11-mile route from Bönigen to Brienz — a village often credited with having the most beautiful street in Europe. The grand finale is the Giessbach Falls, which drop 1,300 feet over 14 stages. Families with less leg power should head for the Axalp plateau, about 5,000 feet up and a 35-minute drive from Brienz, with gentler trails and big views over the lake.
As for a base, you're spoiled. Iseltwald sits conveniently mid-lake and comes with the photogenic Seeburg castle on its shore; Brienz is all timber chalets and train connections; Interlaken offers the full resort-town spread of hotels, restaurants and onward transport into the Jungfrau region.
Why it matters: Lake Brienz packs swimming, boating and serious hiking into one compact, easily reached spot, making it a strong pick for anyone combining an active break with classic Swiss mountain scenery — and a smarter-value alternative to pricier nearby resorts.
