Alton Bay is an unincorporated village in the town of Alton, New Hampshire. It is on Alton Bay, a 4-mile-long cove of Lake Winnipesaukee, which in turn forms the southeasternmost point on the lake. It is part of the Lakes Region, a well-known resort area.
In the nineteenth century, the area functioned as a railroad center. The MS Mount Washington and the ships before it on Lake Winnipesaukee have made Alton Bay a stop since 1872. The Alton Bay Campmeeting Association, a Christian campground organized in 1863 and continuing a year round ministry, is located here. They organize retreats for the summer residents.