Alger Island is a small island located within the Adirondack Park, in New York State. The island lies in Fourth Lake, in the so-called Fulton Chain of Lakes.
Alger Island was called Deer Island in the late 18th century. It was later called Big Island. Alger Island came from the family name of its longtime owners, father and son Mort and Ollie Alger.
Alger Island was purchased by the state of New York on January 16, 1950. Lean-to's were constructed during the 1960s. Today, the island is used as a state campground. Campers need a boat to access the island.