Umsaskis Lake, located about 65 miles west of Presque Isle Maine, is just north of Eagle Lake and is part of the Allagash Wilderness Waterway. The lake is approximately 5 miles in length, covers about 1,222 acres and has a maximum depth of 58 feet. Long lake is just to the north and is connected to Umsaskis Lake via the Thoroughfare. 6 1/2 miles to the south lies Churchill Lake which is joined to Umsaskis Lake by the Allagash River.
The boat launch is at the northern end of the lake, near the ranger's station, on the western side just below the Umsaskis bridge. About 13% of the lakes annual visitors enter from this point. Parking is limited to about 10 spaces, and it is a hand carry in launch area only. Camping can be found at both the northern and southern ends, and like the rest of the Allagash Wilderness Waterway System, is limited to the designated sites only. The name "Umsaskis" means "linked together like sausage" and is of Maliseet origin, who were the native Americans that inhabited the St. Lawrence River Valley.