Wallnau / Fehmarn, Nature reserve on Fehmarn island, Germany.

Wallnau/Fehmarn is a 297-hectare nature reserve on the west coast of Fehmarn, made up of ponds, reed beds, meadows, and a stretch of Baltic Sea shore. It lies on the former Kopendorfer See lakebed, drained from 1866 by Gustav Kröhnke, and is run by NABU as a waterbird reserve.

The shallow bay was cut off from the Baltic about 400 years ago. In 1866 Gustav Kröhnke drained the Kopendorfer See, and the new district was named Wallnau in 1871; storm floods in 1872 and 1874 forced him to sell. Around 1900 a pond estate was created, bought in 1976 by the Deutscher Bund für Vogelschutz and Kreis Ostholstein, and designated a nature reserve on 23 December 1977.

The name Wallnau was given to the new district created when the Kopendorfer See was drained, in 1871. The site is run by NABU as the Wallnau Waterbird Reserve, and its centre in the Altes Gutshaus has an exhibition on bird migration, a restaurant and seminar rooms. A memorial stone at the edge of the reserve recalls the 1970 Love and Peace Festival, where Jimi Hendrix gave his last performance.

Access to the reserve itself requires paying an entrance fee. A path on the crest of the summer dyke allows views over the ponds and reed beds at any time, while NABU's information centre in the old estate house is open from March to October and runs guided walks. Cars approach from the village of Bojendorf to the northeast.

In 1970 the Love and Peace Festival took place on the edge of today's reserve; it was the last festival at which Jimi Hendrix played before his death. A memorial stone now marks the spot, which most visitors pass without noticing.