Hannacrois Creek is a 20.9-mile-long (33.6 km) tributary to the Hudson
River in the U.S. state of New York
. From its source in Westerlo it flows through Dunbar Hollows and over Dickinson Falls to the Alcove Reservoir
. It then passes through Coeymans Hollow and just into Greene County
to its mouth at the Hudson River in Coeymans, New York.