Mermaids Crevice

You'll find this sea cave tucked into Dorset's coastline near Weymouth, accessible at low tide if you're willing to scramble across the rocks. It's a proper little scramble to reach it, but that's half the appeal - you're not going to stumble upon crowds here. The cave itself opens up into a modest chamber where the sound of waves echoes off the stone, and on a calm day you can see the light filtering through from the water's edge.

It's brilliant for anyone who fancies a bit of coastal exploration beyond the usual beach walk. Teenagers and confident walkers will find it fun; younger children might struggle with the rocks and tidal timing. Bring decent footwear and check the tide tables before you go - miss the window and you'll be stuck or turned back.

There's no visitor centre or facilities, and admission is free because there's nothing to pay. Allow a couple of hours if you're making a proper trip of it, including the walk down and time to explore the cave itself. The real value comes from combining it with a stay at one of the nearby parks - Chesil Beach Holiday Park or Waterside are both close by in Weymouth, so you can base yourself there and spend a morning hunting for the cave between other coastal activities. It's the sort of place that rewards a bit of effort and makes for good holiday stories, but don't expect luxury or crowds.