Ogof Pwll Swnd

The entrance to Ogof Pwll Swnd sits tucked into the Carmarthenshire hillside near Llangadog, and the first thing that strikes you is how unassuming it looks. No gift shop, no turnstile, no signs telling you what to expect - just a dark mouth in the rock and the sound of water echoing from somewhere deep below.

It's a proper underground river cave, and you'll be wading through water to explore it. Bring a torch - two, ideally - and waterproof boots or be prepared for wet feet. The passage narrows as you move deeper, and the formations are genuine caving territory: stalactites, flowstone, pools of dark water reflecting your light. It's genuinely atmospheric rather than showy.

This is one for people who actually like caving, not tourists after a quick underground walk. You need to be reasonably fit and comfortable in tight spaces. Kids aged eight and up might manage it, but younger ones will struggle with the physical demands and the confined conditions. Solo walkers and small groups get the best experience here - you can move at your own pace and really take in the geology.

Free admission is a massive draw, though the lack of facilities means it's very much your own expedition. Allow a couple of hours depending on how far you venture. Wear dark clothes and be prepared to get muddy.

Stay at Cosmos Camping nearby (seriously good reviews) or Brecon Beacons Camping if you're planning a caving weekend. Pair this with walking in the Beacons themselves - the cave works best as part of a wider exploration rather than a standalone trip.