Until the separation, in 1884, into Unteriberg and Oberiberg the independent municipality was known simply as Iberg.

[3] Unteriberg is the hometown of noted ski racer Wendy Holdener.

The municipality of Unteriberg lies in the valleys of the Sihl, Waag and Minster rivers, at the southern end of the artificial Sihlsee.

The villages of Unteriberg, Stöcken and Herti all lie on the Minster river close to its confluence with the Waag.

The village of Waag is on its namesake river, whilst Studen is on the Sihl.

Of the rest of the land, 2.9% is settled (buildings or roads) and the remainder (17.6%) is non-productive (rivers, glaciers or mountains).

[5] From the 2000 census[update], 1,880 or 84.7% are Roman Catholic, while 189 or 8.5% belonged to the Swiss Reformed Church.