The Lyd is a river rising at Lyd Head (Corn Ridge in NW Dartmoor) in the Dartmoor national park in Devon in South West England and flowing into the River Tamar beyond Lifton. It runs through Lydford Gorge, the deepest gorge in South West England.

Lydford Gorge (National Trust) is a dramatic feature of the river at Lydford on the edge of the Dartmoor National Park; it is a 1.5-mile (2.4 km) gorge near Lydford on the River Lyd, which is the deepest in South West England. It was formed by the process of river capture, where the start of a nearby river eroded backwards until its origin met the Lyd, diverting its course into the second channel.

Owned and maintained by the National Trust since 1947, the gorge features the 100-foot (30 m) tall White Lady Waterfall and a series of whirlpools known as the Devil's Cauldron.

• Lydford Gorge information at the National Trust