|Location||Kennebec County, Maine|
|Basin countries||United States|
|Max. length||9 mi (14 km)|
|Surface area||5,543 acres (2,243 ha)|
|Max. depth||100 ft (30 m)|
|Water volume||127,371 acre⋅ft (157,110,000 m3)|
|Shore length1||62 miles (100 km)|
|Surface elevation||167 ft (51 m)|
|Islands||Belle Island, Black Island, Blue Bell Island, Cuba Island, Frog Island, Goodwin Island, Grape Island, Green Island, Hersey Island, Hodgdon Island, Horseshoe Island, Island Park, Ladies Delight Light, Leclair Island, Long Island, Lower Sister Island, Lovers Island, Maple Ridge Island, Merrill Island, Molazigan Island, Packards Ledge, Pine Island, Pinkham Island, Richards Island, Scott Island, Sheep Island, Upper Sister Island|
|Settlements||Litchfield, Manchester, Monmouth, West Gardiner, Winthrop|
|1 Shore length is not a well-defined measure.|
Cobbosseecontee Lake, also known as Cobbossee Lake, is a lake located in the towns of Litchfield, Manchester, Monmouth, West Gardiner, and Winthrop Maine. It is the largest lake in the Winthrop Lakes Region at 100 feet (30 m) deep, covering about 8.7 square miles (23 km2) in surface area, a length of 9 miles (14 km), and a shoreline of 62 miles (100 km). The word Cobbosseecontee translates to "plenty of sturgeon" in Wabanaki.
Cobbossee Lake is known for its beautifully irregular shape, which consists of numerous glacial coves, jettys, and islands. It also has the only active inland waters lighthouse in Maine, Ladies Delight Light. The 25-foot (7.6 m) high lighthouse, constructed in 1908, is under the ownership and care of the Cobbosseecontee Yacht Club. Founded in 1904, the club is one of the oldest continually operating inland yacht clubs in the United States. The lighthouse marks the northern edge of a jagged underwater reef that runs down the middle of the lake. The archipelago of islands and exposed ledges are the visible high points of that reef. A state-owned public launch is located on the southwest shore of the lake in East Monmouth. Low hills and ridges surround the lake, and Monks Hill and Allen Hill rise a few miles north of the lake, while a gray line of hills form a barrier near Sabattus.
There are many year-round homes and cottages along the shoreline, with some new developments and gentrification having occurred steadily since the 1990's. The lake is home to Camp Cobbossee, Camp Kippewa, Pilgrim Lodge, and the YMCA Camp of Maine.
Between the 1960's and the early 2000's, Cobbossee Lake's water quality was impaired by severe algae blooms and murky water clarity during the hot summer months, both of which impacted recreation and fish populations quite extensively. However, several cleanup efforts began to surface in the 1970's, likely inspired in part by the EPA's Clean Water Act. A few decades later, the actions had proven successful, and Cobbossee's water quality rapidly improved throughout the 90's and 2000's as phosphorus runoff decreased and the natural springs that feed the lake began to "flush out" many of the remaining pollutants. As of May 2007[update], Cobboseecontee's water quality rivaled that of other clearwater lakes, with many boaters able to see over 8 feet (2.4 m) down, on occasion.
The lake is nationally recognized as one of the top bass-fishing lakes in America, mostly due to its impressive largemouth population. Many of Maine's largest and most aggressive bass come from Cobbossee. There are also many other different types of popular fish that you can find in Cobbosseecontee, which include brook trout, brown trout, rainbow smelt, white perch, yellow perch, bullheads, sunfish and crappie. A popular bass fishing technique on Cobbossee involves casting or slowly trolling around the lake's numerous islands, coves, and ledges.