Purrenstrom
The Purrenstrom is about 9 km long and 2 km wide Tide current in the estuary of the eider that extends to the construction of the Eidersperrwerk plant the lower reaches of the river the full lift of the water is exposed to the North Sea.
North Sea prawns (also North Sea shrimps ) are called leek in large parts of North Frisia . In North Frisian it is called Poorn , in Low German on the Eiderstedt peninsula Purrn , from which the term Purrenstrom probably originated.