In this picture you can see drainage ditches (also called Grüppen in German). They're typical for the landscape around the North Sea. These drainage ditches in the picture are located on a small flat island in the North Sea called Hallig Hooge. You can see the reflexion of the clouds that are illuminated by the setting sun.
<a href="//commons.wikimedia.org/w/index.php?title=User:Lisa-M._Schl%C3%BC&amp;action=edit&amp;redlink=1" class="new" title="User:Lisa-M. Schlü (page does not exist)">Lisa-M. Schlü</a>
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span>