Exmoor is loosely defined as an area of hilly open moorland in west Somerset and north Devon in South West England, named after the River Exe the source of which is situated in the centre of the area, 2 miles NW of Simonsbath. Exmoor is more precisely defined as the area of the former synonymous ancient royal hunting forest, officially surveyed 1815–1818 as 18,810 acres in extent. Even more precisely Exmoor is defined as the remnant of the royal forest of 18,810 acres allotted to the king in 1815, equating to 12/22nds of the total, in acres 10,262 1/4, which was sold to John Knight (1765–1850) in 1818, which comprises the present Exmoor Parish, whose parish church is situated in Simonsbath. The moor has given its name to a National Park, which includes the Brendon Hills, the East Lyn Valley, the Vale of Porlock and 55 kilometres (34 mi) of the Bristol Channel coast. The highest point on Exmoor is Dunkery Beacon; at 519 metres (1,703 ft) it is also the highest point in Somerset.