The trees of Leigh Woods extend over 2 miles along the west side of the Avon Gorge in North Somerset, on the border with Bristol - a mix of ancient woodland and more recent growth, crossed by a network of paths and tracks, and home to many plant species, on account of which the area is protected, both as a national nature reserve and a site of special scientific interest. Most of the ground is fairly level, up to the edge of the gorge where it falls away very steeply, though the wooded land includes two major valleys, Paradise Bottom in the north, containing a permanent stream, and the dry Nightingale Valley near the south edge. The southern third of the woodland is managed by the National Trust, the remainder by the Forestry Commission, and all is very popular, all year round, for walking, running, cycling (including mountain biking, on several dedicated courses), picnicking and looking for wildlife.
Despite the proximity to the Avon Gorge the river is easily glimpsed in only a few places from above, being mostly hidden by the tall trees and steep slopes; Instead nearly all the paths have views only of the trees and the sometimes dense undergrowth. The gorge can instead be seen along a path below, near river level, running parallel to the single-track Portishead Railway which reopened as a freight line in 2001. This path links with others in the woods at five locations, and the whole place offers many different loop hikes. Several locations along the cliffs were quarried in the 18th and 19th centuries, for limestone and celestine, and the exposed rocks now provide an important habitat for wildflowers. They are also occasionally used by climbers, though most activity is on the east side of the river.
One other point of interest within Leigh Woods is Stokeleigh Camp, an Iron Age fort, still easily recognisable by its massive earthworks, forming an approximately horseshoe-shaped enclosure 700 feet across. Although abandoned during Roman times there is some evidence that the site was re-occupied for a while in the Middle Ages.
There are three vehicular access points to Leigh Woods; along North Road in the south (at the head of Nightingale Valley), at the end of the nearby Valley Road, and, the main place, along Abbots Leigh Road a little further north, off the A369. This route is also known as Coronation Avenue, after it was planted with two lines of beech trees to commemorate the Queen's coronation in 1953. The road was formerly one of the two approaches to Leigh Court, a 19th century mansion just beyond the north edge of the woods, on a site of a much older residence, associated with the monks of St Augustine's Abbey, later Bristol Cathedral.
The northern section of the forest in the vicinity of Leigh Court includes some of the oldest trees in the reserve, a varied collection including oak, yew, beech and small-leaved lime; its age is demonstrated by the presence of several indicator wildflower species, such as wood anemone, which are not found in more recent woodland. Also in this area, in the upper reaches of Paradise Bottom, are the remains of an arboretum, established in the mid 1800s, containing amongst other exhibits a grove of Californian redwoods. The trees on the south side of the valley are part of Oak Wood, on a ridge between Paradise Bottom and another, smaller ravine. The patches of ancient woodland extend approximately to an old stone wall towards the south of the reserve, constructed along a parish boundary, and also dividing the Leigh Court estate with the lands of Ashton Court to the south; this later area was once pasture, grazed by cattle and sheep, and became wooded only the over the last hundred years or so. The original grassland survives only in one small area (The Plain), near the Valley Road entrance. Other evidence of the former agricultural use are a scattering of old pollarded trees; new growth was repeatedly cut-down above a certain height, to provide food for the livestock, and now such trees are recognizable by having a thick trunk at the base and relatively thin branches above.
Typical woodland flowers bloom profusely in the spring, when the sunlight still reaches the ground; during summer the flowering plants are mostly restricted to the few open clearings, and along the tracks, though a few less common species can be seen amongst the trees including toothwort, bird's-nest orchid and green-flowered helleborine. Instead, most of the rare plant species are found in inaccessible places along the side of the gorge, growing in crevices and ledges on the limestone bedrock - plants such as Bristol rock cress and western spiked speedwell. A small selection of aquatic and riparian species can be seen in and around Paradise Bottom, the upper reaches of which have several ponds and areas of marsh. The most notable trees are whitebeam and service tree, members of the sorbus genus; over 12 species can be found in the woods, rarest being the Bristol whitebeam, which occurs only in a small area either side of the Avon Gorge.