This sea cave / rock arch is located at the little-known beach of Nanjizal. Located about halfway between Porthcurno and Land's End it is a long walk from the road to get down here.
The tall, narrow slit in the rocks is named Zawn Pyg, which doesn't really do it justice. Hence, it is more commonly known as the "Song of the Sea" which goes some way to hinting at what a magical place this is.
I will be the first to admit this isn't the greatest photo of the place, but it gives an idea of what a stunning natural sight this is.