Unterwalden, translated from the Latin inter silvas[1] ("between the forests"), is the old name of a forest-canton of the Old Swiss Confederacy in central Switzerland, south of Lake Lucerne, consisting of two valleys or Talschaften, now two separate Swiss cantons (or two half-cantons), Obwalden and Nidwalden.

Unterwalden was one of the three participants in the foundation of the Old Swiss Confederacy, named in the Pact of Brunnen of 1315 with Uri and Schwyz.

The division of Unterwalden into two separate territories, Obwalden and Nidwalden, in the early period is less than clear.

Their status as two independent Talschaften appears to develop over the course of the 14th and 15th centuries, while they retain a single vote in the Confederacy.

From this time, there are also two separate coats of arms for the two half-cantons, the red-and-white flag for Unterwalden proper or Nidwalden, while Obwalden had a silver key in a red field.