The Mystic River is a 3.4-mile-long (5.5 km)estuary in the southeast corner of the U.S. state of Connecticut. Its main tributary is Whitford Brook. It empties into Fishers Island Sound, dividing the village of Mystic between the towns of Groton and Stonington. Much of the river is tidal. The location of three large, 19th-century shipbuilding firms, Mystic River is now the home of the Mystic Seaport maritime museum.
The Pequot Native Americans built their first village overlooking the western bank of the Mystic River, called the Siccanemos. The only written records describe this village as existing in the year 1637. There were many hostilities and power struggles between the Native American tribes and English settlers during this time. On May 26, 1637, a military force under the command of John Mason and John Underhill, attacked and destroyed the Pequot village, killing almost everyone and burning the village to the ground.