Wimmer Island/Masnedø Kalv is a small island in Storstrømmen between Zealand and Falster. Wimmer Island/Masnedø Kalv is about 300 m long and about 100 m wide. It overlooks the larger island Masnedø.

Wimmer Island/Masnedø Kalv was part of a military defensive fort’s strategic positions dating from 1912. The fort was a longstanding defensive position for Storstrømmen waters in wars against England and Sweden and Wimmer Island/Masnedø Kalv itself was fitted with a battery of naval artillery. Wimmer Island/Masnedø Kalv was also the first target in the world to be attacked by paratroopers, in 1940 during the German invasion of Denmark.

Before Wimmer Island/Masnedø Kalv came into private ownership, it was used as a grazing area for young cattle from Gammel Masnedøgård and Ny Masnedøgård. The only settlement on Wimmer Island/Masnedø Kalv is a cottage from the 1950s.

Per Wimmer bought this private island in July 2021.