From the Wikipedia page 
Norderney is one of the seven populated East Frisian Islands off the North Sea coast of Germany. It is also a municipality in the district of Aurich in Lower Saxony.
The island is 14 by 2.5 kilometres (8.7 by 1.6 mi), having a total area of about 26.3 square kilometres (10.2 sq mi) and is therefore Germany's tenth-largest island. Norderney's population amounts to about 5,850 people. In 1946 Norderney gained municipal status and belongs to the Aurich "Kreis" (county). On the northern side of the island lies a 14 kilometres (8.7 mi) long sandy beach.
The neighbouring island to the east is Baltrum, which lies about 800m (half a mile) away beyond the Wichter Ee. To the west is the island of Juist, about 3 kilometres (1.9 mi) away on the other side of the Norderneyer Seegatt.