The Arnisee lies at around 1'372 metres in the Maderanertal in the canton of Uri and is a small, quiet mountain lake with an intense mountain backdrop. The water glows in a deep blue-green, surrounded by the steep flanks of the upper Uri alpine region. The lake is little known and rarely crowded – a peaceful contrast to the tourist-developed Lake Lucerne region.

A hiking trail leads from the Bristen valley station in the Maderanertal to the lake and takes around 1.5 hours. The Maderanertal is regarded as one of the wildest and most impressive alpine valleys in central Switzerland; glaciers, cliff faces and rushing streams define the scene. The Arnisee makes a fine stage destination on a day trip into the Maderanertal.

The Maderanertal and Arnisee are reachable by PostBus from Amsteg, which is on the Göschenen–Erstfeld railway line. Amsteg is accessible from Lucerne by train in around 45 minutes. By car, take the A2 motorway, Amsteg-Silenen exit, into the Maderanertal. Parking in Bristen.