Lake Thun – one of the most beautiful bathing lakes in Switzerland

Lake Thun lies in the heart of the Bernese Oberland, in the canton of Bern in the west of Switzerland – and thus in one of the most impressive natural landscapes in Switzerland. It stretches from the town of Thun in the north to Interlaken in the south-east and measures an impressive 48.3 square kilometres. What makes the location so special: to the south and south-west, an Alpine panorama opens up that will amaze you. Mt Niesen, Mt Stockhorn, and in the distance Mt Eiger, Mt Mönch, and Mt Jungfrau – this backdrop accompanies you on every walk, every hike, every morning view out of the window.

The most important tributary is the Kander river, which flows into the lake at Einigen. It brings meltwater directly from the Alps and contributes significantly to what makes Lake Thun so unmistakable: its water quality and characteristic blue colour. The outflow is via the Aare river, which emerges from the lake in Thun and flows from there through the Central Plateau towards Bern. In the Interlaken area, the short Aare river – known as the “Bödeli” – connects Lake Thun and Lake Brienz.

With a maximum depth of 217 metres, Lake Thun is one of the deepest lakes in Switzerland – the average depth is around 135 metres. This enormous mass of water has a pleasant side effect for all bathers: the water warms up slowly and remains refreshingly cool even at the height of summer.

Lake Thun is extremely low in nutrients (oligotrophic). Few nutrients mean less algae, less turbidity, and maximum clarity. In such clear water, blue light is scattered more strongly than all other wavelengths: the result is the intense deep blue that makes the lake so unmistakable. Then there’s the glacier water of the Kander river. It carries very fine mineral particles, which further increase the light scattering. And as the lake is 217 metres deep, the eye doesn’t see the bottom of the lake, but gazes into an almost bottomless blue depth.

Yes, Lake Thun is one of the cleanest lakes in Switzerland. The water quality is regularly monitored by the Canton of Bern and is officially authorised as bathing water. Strict regulations for waste water along the shore ensure that the lake has remained ecologically intact despite its popularity. The water is even treated as drinking water in the region – a quality feature that speaks for itself.

From June to September, official bathing areas, well-maintained lidos and unspoilt shore access invite you to take a dip in Lake Thun. The surface temperature reaches up to 22 to 24 degrees Celsius in midsummer.

Some of the most beautiful bathing spots on Lake Thun:

• Spiez: directly below the castle, with sunbathing lawns and views of the Alps
• Faulensee: quiet, unspoilt, ideal for families
• Hilterfingen and Oberhofen: well-kept lakeside resorts with history
• Gwatt and Thun: easily accessible, urban, with boat hire

All the bathing spots around Spiez can be easily reached on foot or by bike from Hotel Seaside. The reception team will be happy to tell you which bathing spot is particularly recommended – and where the quietest spots are.

If you ask this question, you’ll surprisingly often get the same answer from locals and travellers alike: Spiez. The municipality is located on a peninsula on the southern shore of the lake and has been considered one of the most beautiful bays in Europe for generations – a verdict that is reconfirmed with every sunset. But other places also have their own character: Thun with its lively old town, Oberhofen with its romantic moated castle, Merligen and Hünibach with their peaceful riverside location. Lake Thun has the right place for every taste.

Lake Thun has a circumference of around 54.5 kilometres. The well-signposted Lake Thun circular trail leads through vineyards, along promenades, through villages and along quiet shores – constantly offering new perspectives of the water and the mountains. If you don’t want to complete the whole tour in one go, you can choose your own stages and close the gaps by boat or train.

Spiez is right in the middle of it all – between the lake, mountains, and everything that makes a holiday in the Bernese Oberland special. And Hotel Seaside is the perfect base camp for this: with a view of the most beautiful bay in Europe and a team that knows your wishes before you say them.