Ogof Pen Eryr

The entrance to Ogof Pen Eryr sits just above Crickhowell, a proper limestone cave that rewards the short walk from the car park with something genuinely different. Once you're through the mouth of the cave, you'll find yourself in a system that's less touristy show-cave and more genuine caving experience - expect narrow passages, underground streams, and the kind of formations that make you realise why people get obsessed with caves.

It's free, which is brilliant. You'll need a torch - bring a decent one, not your phone's pathetic flashlight - and watch your head in places. Most people can navigate the main passages comfortably enough, though some sections require a bit of scrambling. The walk from the village takes maybe fifteen minutes. Allow a couple of hours if you're exploring properly, though keen cavers will spend longer.

Families with primary-school age kids will get plenty out of it, assuming they're not spooked by tight spaces and darkness. Teenagers often find it more interesting than yet another stately home. For walkers based at Cwmdu Campsite nearby, this works perfectly as a half-day activity - combine it with a proper leg-stretcher on the hills above Crickhowell and you've got a solid day sorted.

The cave's accessible enough in summer, though winter can bring water issues. Spring or early autumn tends to be ideal. It's the kind of place that feels properly wild compared to the managed attractions you'll find elsewhere - exactly what you want if you're after something with actual character.