On Flat Holm in the Mouth of the Severn, 4.5 km South East of Penarth, Cardiff.
A plainly marked path leads to the entrance and it is said that smugglers used the cave for the storage of contraband.
Description
The entrance is half way down the cliff on the NE side of the island. A low entrance leads to three chambers, perhaps with evidence of mining. A blocked opening in the last chamber indicates further passage.
