Untersee

Untersee is a mountain lake in Arosa, in the Swiss canton of Graubünden. It sits at roughly 1,691 m above sea level and is the lower of the two lakes inside the resort's built-up area, below the larger Obersee. Locals and visitors treat it as Arosa's natural swimming lake, and it is listed at about 17 m deep.

Where is Untersee and how does it relate to Obersee?

Arosa has two lakes within the village: the Obersee (about 1,734 m) above and the Untersee below. The Mittelbach stream links them. Untersee lies away from the busiest part of the centre, ringed by alpine meadows and conifer forest, at approximately 46.779 N, 9.682 E. The name is common across Switzerland and Germany, so make sure you are heading to the lake in Arosa and not to the Untersee arm of Lake Constance.

Can you swim here?

Yes, and swimming is the main reason to come. The Strandbad Untersee is a fully equipped lido on the shore, with a sandy beach, sunbathing lawns, diving platforms and a heated paddling pool for children. Mountain water stays cool even in summer, so plan your swim for warm, sunny days. The bathing season runs through summer; check current opening hours with Arosa Tourism before you travel.

Which walk starts here?

Untersee is the trailhead for a circular four-lake hike. The route leads to the Stausee reservoir (also called Iselsee, about 1,606 m), on to the small Grüenseeli (about 1,811 m) and then to the Alteinsee. It makes a full day out for families and regular walkers, mixing the lido shore, a dam, higher-altitude ponds and views of the peaks around Arosa. Carry water, a layer for changing weather and shoes with solid grip.

How do you get to Untersee?

Arosa is the terminus of the railway from Chur. The Rhaetian Railway ride takes about an hour and winds over many bridges and through tunnels. From Arosa station you can walk to the lake, and local buses cover the resort. If you drive, leave the car in a village car park, since traffic in the centre is restricted.

When is the best time to visit?

June to September suits swimming and hiking best: trails around the lakes are clear of snow and the lido is open. At this altitude mornings can be cold and the weather shifts quickly. In winter Arosa is a ski resort and the lakes freeze, so Untersee becomes part of the snowy scenery rather than a destination in itself.

What else is nearby?

The Obersee is the bigger lake in the centre of Arosa, with a fountain and, in summer, rowing boats, pedal boats and stand-up paddle boards for hire. You can link both shores in a single stroll along the Mittelbach. Further out are more mountain lakes, including the Grüenseeli and the Scheideggseeli, reached by marked trails.

Frequently asked questions

How high is Untersee in Arosa? About 1,691 m above sea level, a little lower than the Obersee.

Is there a beach at Untersee? Yes. The Strandbad Untersee has a sandy beach, sunbathing lawns, diving platforms and a heated children's pool.

Are Untersee and Obersee the same lake? No. They are two separate lakes in Arosa joined by the Mittelbach. The Obersee is larger and central, while the Untersee is lower down and serves as the natural bathing lake.

How deep is Untersee? Tourism sources give a depth of about 17 m.