The O Brook is a short tributary of the West Dart River

West Dart River

The West Dart River is one of the two main tributaries of the River Dart in Devon, England.Its source is near Lower White Tor 1.5 km north of Rough Tor on Dartmoor. It flows south to Two Bridges, then south east past Hexworthy to meet the East Dart River at Dartmeet...

 on Dartmoor

Dartmoor

Dartmoor is an area of moorland in south Devon, England. Protected by National Park status, it covers .The granite upland dates from the Carboniferous period of geological history. The moorland is capped with many exposed granite hilltops known as tors, providing habitats for Dartmoor wildlife. The...

 in Devon

Devon

Devon is a large county in southwestern England. The county is sometimes referred to as Devonshire, although the term is rarely used inside the county itself as the county has never been officially "shired", it often indicates a traditional or historical context.The county shares borders with...

, England. It lies near the village of Hexworthy

Hexworthy

Hexworthy is a hamlet on Dartmoor, in Devon, England. It lies on the West Dart River a mile upstream from Dartmeet. Historically in the parish of Lydford, since 1987 it has been in the civil parish of Dartmoor Forest....

, and the lower part of the stream forms the boundary between the parishes of Holne

Holne

Holne is a village and civil parish on the southeastern slopes of Dartmoor in Devon, England. A community has existed here since at least the 11th century, and today a population of around 250 people is served by a church and a public house, the Church House Inn.-Village:The Church of St Mary the...

 and Dartmoor Forest

Dartmoor Forest

Dartmoor Forest is a civil parish in Devon, England. It was formed in 1987 by the splitting of the former parish of Lydford. It covers about entirely within Dartmoor National Park, and is the largest parish in Devon. Despite its size its population in 2001 was only 1,619....

 (formerly Lydford

Lydford

Lydford, sometimes spelled Lidford, is a village, once an important town, in Devon situated north of Tavistock on the western fringe of Dartmoor in the West Devon district.-Description:The village has a population of 458....

). An earlier form of the name was Ocbroke, and it apparently means "Oak Brook", although oaks are rare in the area.

The stream is notable for its historic tin mines

Dartmoor tin-mining

The Dartmoor tin mining industry is thought to have originated in pre-Roman times, and continued right through to the 20th century. From the 12th century onwards tin mining was regulated by a Stannary Parliament which had its own laws....

.

A rock formation on the stream bank, known as the Dragon's Den, gave rise to the legend of the Dragon of the O Brook.