Barhatch col (21% max gradient)

The road climbs relentlessly through thick woodland near Guildford, and that's rather the point of Barhatch col. This Surrey lane hits a punishing 21% gradient - one of the steepest in the south-east - and cyclists, runners, and the just-plain-curious come here to test themselves against it.

It's not long, which is both good and bad. You'll be done in minutes if you're fit; utterly destroyed in ten if you're not. The tarmac is decent enough, though the trees crowd in tight and it can feel claustrophobic on a grey day. On a clear one, though, there's something properly satisfying about grinding up those switchbacks and knowing you've tackled something genuinely tough.

Cyclists rate it highly - it's become a bit of a cult spot for hill repeats and training. Runners sometimes give it a go, though the surface isn't ideal for that. Casual walkers will find it manageable but not particularly scenic; you're really here for the challenge, not the views.

There's no visitor centre or facilities - it's just a road. Free to access, obviously, and open whenever. Allow twenty minutes to walk it comfortably, less if you're on a bike and fit enough to mean it.

If you're camping at Care Ashore Campsite or the nearby Glamping Holiday, both within easy driving distance, Barhatch makes a solid morning out when the weather's decent. Worth the detour for anyone who enjoys a proper physical challenge, less so if you want a casual stroll.