most wooded county in England, with 22.4% coverage compared to a national average of 11.8% and as such is one of the few counties not to recommend new woodlands in the subordinate planning authorities' plans. Box Hill has the oldest untouched area of natural box woodland in the UK, one of the oldest in Europe. In 2020 the Surrey Heath district had the highest proportion of tree cover in England at 41%. Surrey also contains England's principal concentration of lowland heath, on sandy soils in the west of the county. Agriculture not being intensive, there are many commons and access lands, together with an extensive network of footpaths and bridleways including the North Downs Way, a scenic long-distance path. Accordingly, Surrey provides many rural and semi-rural leisure activities, with a large horse population in modern terms. The highest elevation in Surrey is Leith Hill near Dorking. It is above sea level and is the second highest point in southeastern England after Walbury Hill in West Berkshire which is . Surrey rivers The longest river to enter Surrey is the Thames, which historically formed the boundary between the county and Middlesex. As a result of the 1965 boundary changes, many of the Surrey boroughs on the south bank of the river were transferred to Greater London, shortening the length associated with the county. The Thames now forms the Surrey-Berkshire border between Runnymede and Staines-upon-Thames, before flowing wholly within Surrey to Sunbury, from which point it marks the Surrey-Greater London border as far as Surbiton. The River Wey is the longest tributary of the Thames above London. Other tributaries of the Thames with their courses partially in Surrey include the Mole, the Addlestone branch and Chertsey branch of the River Bourne (which merge shortly before joining the Thames), and the Hogsmill River, which drains Epsom and Ewell. The upper reaches of the River Eden, a tributary of the Medway, are in Tandridge District, in east Surrey. The River Colne and its anabranch, the Wraysbury River, make a brief appearance in the north of the county to join the Thames at Staines. Climate Like the rest of the British Isles, Surrey has a maritime climate with warm summers and cool winters. The Met Office weather station at Wisley, about 6.5 miles (10 km) to the north-east of Guildford, has recorded temperatures between (August 2003) and (January 1982). From 2006 until 2015, the Wisley