Ogof Iron

Darkness swallows you whole the moment you step into this limestone cave system on Anglesey's rugged coast. Ogof Iron sits just outside Holyhead, where the sea has carved out a network of chambers and passages over millennia. The entrance might fool you into thinking it's just another coastal crevice, but venture deeper and you'll find yourself in a proper underground adventure.

Cavers and geology enthusiasts will get the most from this experience, though anyone with a torch and a sense of adventure can explore the accessible sections. The formations inside are properly impressive - stalactites hang like ancient chandeliers while flowstone cascades down the walls in frozen waterfalls. It's not a tourist cave with handrails and lighting, so you'll need to bring your own illumination and sturdy footwear.

Families staying at nearby Silver Bay Holiday Park or Sandy Beach Caravan Park will find this makes a cracking half-day excursion, especially if the weather turns. Just remember this isn't a casual stroll - the cave requires a bit of scrambling and isn't suitable for very young children or anyone uncomfortable in confined spaces. Check tide times before you go, as the entrance can flood during high spring tides.