The Blackwater Valley is an 18-mile green corridor, containing two Sites of Special Scientific Interest (SSSIs), three nature reserves and another 31 designated wildlife sites. It’s a landscape frequented by kingfishers, damselflies, water voles, lapwings, roe deer and otters – but what makes this an unlikely spot for wildlife, and an unusual conservation success story, is that the valley is a working gravel extraction site.

STARTPark at the Horseshoe Lake Activity Centre, on Mill Lane. Walk right, past the activity centre and through a gate. Continue on the path, through a kissing gate, then cross a lane and pick up the path. Cross several stiles and continue to a lane. Turn left then, after 100m, right through a metal gate into woodland. This patch of woodland, which is carpeted in bluebells in spring, has been untouched since 1750 and harbours woodpeckers, nuthatches and roe deer. Where the path splits, turn right then keep straight ahead, bearing left at a junction, and following the track past houses. Ignore a National Trust sign on the right and continue downhill until you reach Lower Sandhurst Road.

1 3/4 MILES Turn right, and after 500m turn right up Dell Road. As the slope gets steeper, look back for views over the Blackwater Valley, with the North Downs Way running along the ridge. Turn left at the road and keep left at the next junction. Opposite the white Court Cottage, turn left and walk along a new permissive footpath through farmland, which is currently being managed to create new habitats for wildlife. Turn right at the lane, then left at the corner of Cricket Hill, before bearing left through a kissing gate. Cross the road and continue along a track. Turn left at Field House; on your right is a plaque marking the spot where, in 1501, Henry VII and his sons Arthur and Henry, out in hunting in the woods, heard news of the arrival of Prince Arthur’s bride, the Infanta Katherine of Aragon.

3 3/4 MILES Join the Blackwater Valley Path, then cross a stream, go through a kissing gate and follow the path around the edge of the field to a road. Cross the road and pick up a path between the river and gravel pits. Gravel extraction has sculpted this landscape for the last 60 years, and today the valley presents a perfect example of how we can manage our environmental impact to create new habitats for wildlife. The lake on your left is less than a year old, but already water birds and waders have moved in. Follow the path between gravel pits and the river, which is named after the black, peaty soil that makes up its bed.

5 MILES Cross a conveyor belt and leave the gravel pits behind, entering Moor Green Lakes Nature Reserve, a series of lakes lined with reeds and teaming with wildlife. The Blackwater Valley Countryside Partnership have turned these excavated gravel pits into lakes, wet meadows, reed beds and woodlands, encouraging wildlife and wild flowers to flourish. In summer wild flowers cover the banks, 30 species of dragonflies and 32 species of butterflies live here, and you may be lucky enough to spot an adder or common lizard sunning itself on the path. Recently a number of otter spraints have been found, a sure sign that water quality is improving. Carry straight on a junction of paths, and later take the lower path beside the river. Just before you reach Mill Lane, take a left along a boardwalk to return to the car park.