The
River Plym is a
river in
Devon, England. Its
source is some 450m (about 1500 ft) above
sea level on
Dartmoor, in an upland marshy area called Plym Head. From the
upper reaches, which contain
antiquities and
mining remains, the river flows roughly southwest and enters the sea at
Plymouth Sound. The river passes to the east of (and gives its name to) the city of
Plymouth — the settlement was historically known as Sutton. Its tidal estuary is known as the
Laira and the final part is called
Cattewater. It is approximately 30 km (about 20 mi) long.