The Obersee lies at 983 metres in the Oberseetal above Näfels in the canton of Glarus: a shallow mountain lake of around 24 hectares in a broad valley basin. The walls of the Brünnelistock rise above the northern shore, the Rautispitz to the west. In calm conditions the clear water mirrors the entire chain of peaks.

A flat walking path of around three kilometres circles the lake, walkable in about an hour and passable with a pram. Along the shore are barbecue and picnic spots, a campsite with a natural swimming pool and the Berghotel Obersee. Longer routes lead up the Rautispitz or along the Ahornen circular trail. The hike to the Klöntalersee over the Lachengrat takes around 5 hours and is a full day tour.

The Obersee is reachable on foot from Näfels in around 1 hour 45 minutes. By car, a narrow, steep mountain road leads from Näfels into the Oberseetal in about 15 minutes, where parking is available. Näfels-Mollis is connected by train from Zurich in around 55 minutes; from there an on-demand bus runs to the lake and must be booked the evening before.