The Connecticut Lakes are a group of lakes in Coos County, northern New Hampshire, United States, situated along the headwaters of the Connecticut River. They are accessed via the northernmost segment of U.S. Route 3, between the village of Pittsburg and the Canada port of entry south of Chartierville, Quebec. The lakes are located within the boundaries of Pittsburg, but are far from the town center. Connecticut Lakes State Forest adjoins them.
There are four lakes: First, Second, Third and Fourth Connecticut Lake, numerically running south to north. The lakes decrease in size and increase in elevation, sequentially from first to fourth. The fourth lake is the source of the Connecticut River. The first three lakes can be viewed and accessed from U.S. Route 3, while the only access to the fourth lake is via the Fourth Connecticut Lake Trail, which goes in and out of Canada. All lakes are north of the 45th parallel.
Lake Francis lies to the south of the four Connecticut Lakes. It is a man-made reservoir and the last of the major lakes along the Connecticut River in northern New Hampshire.