The River Exe in England rises near the village of Simonsbath, on Exmoor in Somerset, near the Bristol Channel coast, but flows more or less directly due south, so that most of its length lies in Devon. It reaches the sea at a substantial ria on the south (English Channel) coast of Devon. Historically, its lowest bridging point was at Exeter, though there is now a viaduct for the M5 motorway about 3 km south of the city centre.
The river fuelled Exeter's growth and relative importance in medieval times and the city's first industrial area was developed at Exe Island, created by a series of leats to the west of the city. The island was home to numerous watermills producing paper and textiles; it also created valuable land through drainage of the marshlands.
Tides on the river are limited at Countess Wear, the site of a weir commissioned by the Countess of Devon in the 13th century. The Exeter Canal bypasses this weir to enable ships to reach Exeter Quay. At high tide, the estuary forms a large body of water that is heavily used for water sports especially sailing, windsurfing and water skiing.
Railways run along both sides of the estuary. The Avocet Line from Exeter to Exmouth on the eastern side, and the South Devon main line on the western. The latter is on a causeway, the South Devon Railway sea wall from Powderham to Dawlish Warren. The Exmouth to Starcross Ferry carries passengers across the mouth of the estuary during the summer months, linking the harbour at Exmouth with a pier adjacent to Starcross railway station on the South Devon main line.