Ariel Cave (Blacknor Hole)

The cave mouth opens onto Portland's rocky shoreline like a dark eye watching the sea. Ariel Cave, also known as Blacknor Hole, is a natural sea cave carved into the limestone cliffs - the sort of place that gets under your skin because it feels genuinely wild and properly remote, even though Weymouth is barely down the road.

What you're really doing here is scrambling down to the shore and exploring the cave entrance itself. It's not a vast cavern system - more a substantial hollow in the rock that floods at high tide - but that's rather the point. The approach alone feels like an adventure: steep steps, rough stone underfoot, the sound of waves echoing off the cliff face.

This works best for older kids and adults who fancy themselves a bit adventurous. Toddlers will struggle with the descent, and anyone nervous about heights should probably give it a miss. Allow a couple of hours if you're doing it properly - more if you want to sit and just listen to the sea working away at the rock.

Timing matters enormously. Go at low tide or you won't get far into the cave mouth. Check the tides before you head out from Weymouth, because getting caught out here would be grim. The cave is free to visit, though the access is via public footpaths.

If you're staying at Chesil Beach Lodge Park or one of the other spots along this coast, it's an easy half-day excursion. Not quite as polished as some Dorset attractions, but that's precisely what makes it worth the effort.