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, Connecticut between the towns of
Stonington. Much of the river is tidal. The Mystic River was the location of three large shipbuilding firms during the 19th-century, and it is now the home of the
Mystic Seaport maritime museum. The name Mystic is derived from the Pequot term "missi-tuk", describing a large river whose waters are driven into waves by tides or wind, according to the Mystic River Historical Society.