Hincaster Tunnel.

Walk south from Kendal along the Lancaster Canal towpath and you'll stumble on something genuinely odd - a Victorian tunnel burrowed straight through solid rock. Hincaster Tunnel is exactly what it sounds like: a 300-metre bore carved out in the 1820s so canal boats could pass underneath without having to divert around the hill. You can walk right through it.

The experience is properly atmospheric. Water laps at your feet, the air gets colder, and daylight shrinks to a pinprick behind you as you venture into near-total darkness. It takes maybe ten minutes to cross the whole thing, depending on how carefully you're picking your way. Bring a torch - honestly, you'll want one. The walls are slick with moisture and mineral deposits, and the beam picks out Victorian engineering marks left by whoever cut this thing 200 years ago.

It's free and takes minimal time, which makes it brilliant for a quick detour if you're basing yourself at Kendal Caravan and Motorhome Club Campsite or The Ashes Caravan Park. Walkers find it genuinely interesting rather than just Instagram-friendly. Kids over about eight will find it brilliant; younger ones might struggle with the darkness and echoes, to be honest.

Worth the short walk from Kendal town centre, particularly if you're already exploring the canal corridor. Go in daylight, take a proper torch, and wear shoes you don't mind getting wet. The tunnel itself demands respect - it's a proper feat of Victorian ambition.