Kennall Vale is a steep, wooded ravine in the middle of Cornwall's mining country, and for a hundred years its stream was used to make gunpowder. The mills, built in the early nineteenth century, produced the powder that miners used to blast tunnels and shafts in the tin and copper mines, and the valley was chosen because it had water, privacy and trees to absorb explosions. The gunpowder works closed in the early twentieth century, and the buildings fell into ruin. Now the old mill walls stand in a thick green wood of oak, beech and ash, with moss on every stone and a leat, the stone-lined channel that brought the water, still threading through. It is one of the most atmospheric places in west Cornwall, and a nature reserve.
A walk through the vale takes forty minutes. Paths run along the stream, past a waterfall and the ruined mill houses, under tall trees and across stepping stones. After rain the stream is loud and brown, and the whole place drips. Bats roost in the ruins in winter, and in spring bluebells and wild garlic cover the ground. It is a place for a gentle pause rather than for a long visit. The vale is part of the UNESCO-listed Cornish mining landscape, because the gunpowder was as much a part of the industry as the engines.
The roads to the vale are narrow, deep lanes with high hedges, between small villages such as Stithians and Ponsanooth. They twist and rise in tight bends, with little visibility, and surfaces can be rough, so take them slowly. Tractors and delivery vans appear without warning, and in the lanes between the hedges a bike is an advantage. Stithians reservoir, close by, is a pretty stretch of water, and the village has a small shop.
Penryn, four kilometres away, has fuel and a few services, and the nearby port of Falmouth has everything, with a harbour, cafes and an excellent maritime museum. A pasty from a bakery is the right lunch. Wear boots, since the paths can be muddy, and bring a waterproof, because Cornish rain is fine and persistent. The best time is spring, when the wood is bright green.