[3] The Great Chazy River flows along the southeastern edge of the hamlet, dropping 150 feet (46 m) in elevation in 1.7 miles (2.7 km).

According to the United States Census Bureau, the Altona CDP has a total area of 1.7 square miles (4.4 km2), all land.

[4] As of the census[6] of 2000, there were 1,056 people, 140 households, and 89 families residing in the CDP.

30.7% of all households were made up of individuals, and 19.3% had someone living alone who was 65 years of age or older.

The census-designated place is within the Northern Adirondack Central School District.