The area of the lake is 44.7 square kilometres (17.3 sq mi), and the area of its basin is 709 square kilometres (274 sq mi).

There are three villages on Lake Undozero, Skarlakhta, Pogost, and Mezen.

The railway belongs to the Department of corrections, and as a matter of fact, there are settlements around the village of Skarlakhta inhabited by convicted criminals who have previously served a part of their jail term.

Undozero is popular as a starting point for rafting down the Undosha.

Therefore, the rafters start in Skarlakhta and finish at Lake Kenozero.