This is a photo of a roundish rock in shallow water.  The light is from behind, so there is a shadow towards the viewer.  Within the shadow you can see smaller rocks under the water, while the sunshine on the water outside the shadow obscures the smaller rocks a bit.  The sun is also shining off some wet rocks in the background.
<a href="//commons.wikimedia.org/w/index.php?title=User:BethGwynne&amp;action=edit&amp;redlink=1" class="new" title="User:BethGwynne (page does not exist)">BethGwynne</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>