Washed by the sea

Today's picture is a very simple image. A pool of sea water just a few centimetres deep and the pebbles under the water. 
I thought the interplay of light, refraction and shadows on the pebbles was interesting.
The coast on this corner of the island of Härnön is spectacular, as I hope the extra of the Pilot's cottage indicates. HD has written in more detail about the Pilot's cottage and the area. It's one of her choices for a CBPOI.