Alton Bay is an unincorporated community in the town of Alton in Belknap County, New Hampshire, United States, and is located on Alton Bay, a 4-mile-long cove of Lake Winnipesaukee which forms the southernmost point on the lake. The village is part of the Lakes Region, a popular resort area of the state. Alton Bay is located at the intersection of New Hampshire Route 11 and Route 28A, 1 mile north of the center of Alton.