Jadebusen, formerly Jade or Jahde, is a bay on the North Sea coast of Germany. About 180 km² (70 mi²) in area, it was largely created by storm floods during the twelfth and sixteenth centuries. During this period it was connected in the East to the river Weser. This connection was closed between 1721 and 1725 by dikes reconnecting Butjadingen to the mainland as a peninsula. In the West the Jadebusen was extending far into the Frisian peninsula. From the early sixteenth century a number of dikes were built against the storm floods and to arable land. The main dike, Ellenser Damm, was built between 1596 and 1615 based on an agreement between the principalities of East Frisia and Oldenburg. Jadebusen is a part of the German Wadden Sea National Parks. The port of Wilhelmshaven is on the western shore of the bay.
