This is the hidden little beach of Lankidden Cove on the eastern side of the Lizard Peninsula.
The beach all but disappears at high tide leaving just the pebbles you can see. However, as the tide drops it reveals this lovely white sand and opens up lots of nooks and crannies to explore.
Its not easy to get to though. It is a fair old walk along the coastpath followed by a steep scrabble down ending in a rope. Worth it though.