Seboomook Lake is an unorganized territory in Somerset County, Maine, United States.

Seboomook Lake is a reservoir on the West Branch Penobscot River.

The reservoir extends upstream from Seboomook Dam in Seboomook Township, through Plymouth Township, to the confluence of the North Branch and South Branch Penobscot River in Pittston Academy Grant.

[3] The territory consists of 39 whole townships[6] plus portions of four other townships shared with Northeast Somerset (Brassua, Soldertown (T2 R3 NBKP), Thorndike, and Tomhegan): At the 2000 census there were 45 people in 22 households, including 11 families, in the unorganized territory.

There were no families and 11.1% of the population living below the poverty line, including no under-eighteens and none of those over 64.