More than two-thirds of the total area of Telemark—more than 10,000 square kilometres (3,900 sq mi)—belong to the traditional region of Upper Telemark.

Upper Telemark has a varied and often scenic landscape, with many hills, mountains, valleys and lakes.

Upper Telemark is known for its folk traditions within music, clothing, handcrafts, food and architecture.

Whereas Lower Telemark was traditionally dominated by the burghers of the cities, Upper Telemark was for centuries dominated by a close-knit "aristocracy of officials" comprised by a handful of families which monopolized the state and church offices in the region, notably the families Paus, Blom, Ørn, and Morland.

Coll has written that the border is defined by the mountainous cleft, that is formed by the lakes Bolkesjø, Ørvella, Øverbø-moen, Seljordsvatnet, Flåvatn, and Fjågesund or Bjårvatn.