Lake Congomond is a 477-acre great pond located off of MA-168 on the Massachusetts-Connecticut border in Southwick. Lake Congomond is comprised of three basins connected by waterways that are navigable to all but the largest of boats. The North basin (47 acres) has an average depth of 21 feet and a maximum of 46 feet, the middle basin (284 acres) has an average depth of 22 feet with a maximum of 42 feet, and the south basin (146 acres) has an average of 16 feet with a maximum of 27 feet. Water clarity varies among basins, and the bottom is generally mud with scattered areas of gravel and cobble. Aquatic vegetation is patchy and generally not abundant due to the application of herbicides. With the exception of the east side of the north basin, the shoreline is heavily developed with year-round residences. Congomond Lake hosts multiple competitive bass tournaments each year and receives heavy recreational use during summer.

The town of Southwick manages two public boat ramps in the middle basin where watercraft may be launched for a fee. The north ramp is located off Point Grove Road on the northern shore of the middle basin and is a double concrete ramp with an adjacent fishing pier, a small picnic area, and a parking lot suitable for roughly 30 trailers. The south ramp is located off Berkshire Road on the southeastern shore of the middle basin and is a single concrete ramp (with a sharp drop-off) and an adjacent parking area suitable for roughly 18 trailers. Shoreline access is limited to areas adjacent to the ramps.