Underwater abstract

For the Abstract Thursday theme of "transparency". Thanks to Ingeborg for hosting AT.  
The water in the bay was very clear and transparent this morning. I could see all the rocks and shells under the water, and what really caught my eye was the reflection of a tree over some of them, making them darker than the others. I took this from the dock. 
I got mushroom moussaka ready for supper before I went for a walk, so I was out later than usual. I saw only one other person, an older man and his dog heading for his car when I got out of mine. Very quiet and peaceful. 
Frosty this morning but raining now in late afternoon.