The Breakwater is a two-story wood frame structure, set at the southern end of the narrow peninsula projecting south from Mount Kineo into Moosehead Lake, Maine's largest lake. The main block is set on stone piers and topped by a shingled hip roof, with a side ell of 1-1/2 stories that is gambrel-roofed. The primary facade faces the lake to the south, with a two-story recessed porch at its center, and flanking multiwindow bays on either side. A beltcourse of trim separates the first and second floors, rising in gentle keystoned arches above the windows of the side bays. A hip-roof dormer pierces the roof above the porches. The western facade is somewhat similar in appearance; the first-floor porch has been glassed in, and there is an eyebrow dormer above the porches. Windows on the first floor are twelve-over-one on the first floor and six-over-one on the second. The porch balustrades are diamond-shaped woodwork.