A group of mudflat hikers on the Wadden Sea near Pieterburen, Netherlands.
The walk is dangerous as the mud can sometime sink in without warning.
There are marked routes and is important not deviate from the path.
The Wadden Sea is incredibly rich in biodiversity.
Many fish species use the Wadden Sea as a nursery using the shallow basin to raise the young.
Once they become adults, they migrate to the North Sea.
North Atlantic right whales and gray whales that frequented the are were completely wiped out by whaling.
The size of the Wadden Sea itself has reduced to about 50 percent its original size.
