Thompson Lake is one of the most pristine Lakes in Maine. It is twelve miles long and averages two miles in width. It is made up of 4,426 acres or nearly seven square miles. Maximum depths of 121 feet and a mean depth of 35 feet. Thompson Lake is rated one of the ten best bodies of water in Maine for water quality. The water clarity is up to 35 feet in depth. It is spring fed by the Poland Spring Aquifer.
The lake is located in 4 towns, Poland, Oxford, Otisfield and Casco with approximately 1200 homes and cottages