They are the only German islands not in the vicinity of the mainland.date=May 2019 They lie approximately 69 kilometers by sea from Cuxhaven at the mouth of the River Elbe.date=May 2019 During the period of British possession, the lyrics to "Deutschlandlied", which became the national anthem of Germany, were written on one of the islands by August Heinrich Hoffmann von Fallersleben in 1841, while he was on holiday there.date=May 2019