The Isinglass River is a 15-mile-long (24 km) river in Strafford County in southeastern New Hampshire, United States. It rises at Bow Lake in the town of Strafford, but is also fed through its tributaries by Ayer's, Nippo, Round and Long ponds in Barrington. The Isinglass flows east to meet the Cochecho River below Rochester. The river is part of the Piscataqua River watershed.