Charleston Lake is often referred to as the "Hidden Jewel" of Eastern Ontario. Charleston Lake sits atop the Frontenac Arch, the ridge of ancient granite connecting the Canadian Shield and the Adirondack Mountains. It is the largest lake of the Frontenac Arch Biosphere Reserve which is the twelfth UNESCO designation in Canada.
Charleston Lake is located in the Township of Athens and Leeds and the 1000 Islands. It covers an area of just over 2500 hectares or 26.2 sq. km. with a maximum depth of 91.1 m. and has a watershed surface area of nearly 290 sq. km. and has over 80 islands. The physical character of Charleston Lake is very unique for it is cradled in two distinct bedrock types: granite and sandstone. For the most part, the southwest end of the watershed is on igneous bedrock and the northeast portion is on sedimentary rock. The watershed has a great biodiversity of plants and animals such as the three-needle Pitch Pine which is common to New Jersey and not found anywhere else in Canada.
Natives once sheltered under rock overhangs on the shores of this cold-water lake north of the St. Lawrence River. Then wealthy Victorian cottagers summered here. The rugged look of the north blended with the south still draws hikers and canoeists to these scenic shores and winding trails.