The sea sides of the megaripples north of Amrum are populated at their highest points again and again with small seal colonies. Here I have focused the motive on exactly this place and one sees on the small ripple structures well the seals lie. This sandbank is yellowish, which probably also gives the water here its strong green coloration.
You can see in this picture how shallow the water in front of the sandbank must be. There the ripple structures continue.