Alton sits at the southern tip of Lake Winnipesaukee in Belknap County, where the lake narrows into Alton Bay. The town's identity is closely tied to the bay's marina, seaplane base, and summer boating traffic.

Alton Bay's boardwalk and marina anchor a small summer tourism economy, while the surrounding hills and forest offer hiking and snowmobiling in the off-season. The town's year-round population is considerably smaller than its summer population, which swells with lake-going visitors and seasonal residents.

Housing ranges from modest inland homes to premium lakefront property around the bay, with prices tied closely to proximity to the water. Alton draws retirees, boaters, and seasonal homeowners seeking a quieter alternative to the busier Winnipesaukee towns to the north.