Suncook is a census-designated place (CDP) in Merrimack County, New Hampshire, United States. The population was 5,362 at the 2000 census. Half of Suncook village is located in the town of Pembroke, with the remainder in Allenstown. The village of Suncook formed along the falls of the Suncook River, which drops 70 feet (21 m) in one-half mile (1 km) just before joining the Merrimack River. Much of the center of the village is occupied by 19th-century factory buildings which once used the river's energy for hydropower. The buildings have now largely been converted to other uses.