Unterwalden, a central canton of Switzerland, bounded N. by Lucerne and Schwytz, E. by Uri, S. by Bern, and W. by Lucerne; area, 295 sq. m.; pop. in 1870, 26,116, of whom 25,687 were Eoman Catholics. It is divided into Upper and Lower Unterwalden, the capital of the former, which is the western division, being Sarnen, and that of the latter Stanz. Much of the surface is covered by mountains, which traverse the canton in different directions, and in the south attain a height of upward of 10,000 ft. above the sea. The remainder consists of four principal valleys, which have a general slope toward Lake Lucerne on the N. frontier, into which the chief rivers, the Melch and the Aa, discharge nearly all the drainage of the canton. There are several small lakes, and about one fourth of the area of Lake Lucerne belongs to Unterwalden. The geological formation is chalk, and the canton is remarkable for a great number of caverns. Little of the land is level enough for agriculture, but the pastures are excellent, and cattle constitute the chief wealth of the inhabitants. There are extensive forests. Apples, pears, and chestnuts are raised in great quantities. German is the language of the canton. The government is democratic, and every male inhabitant of 20 years and upward is entitled to vote.
Unterwalden was one of the three original cantons of the Swiss confederation.