Grønsund is a strait in Denmark separating the island Falster from the islands Møn and Bogø. Grønsund's maximum depth is at approx. 20 metres and the width is between 1 - 4 km. Storstrømmen channel is situated to the west and Stege Bugt lies to the north between Zealand and Møn. A ferry crosses the channel in the summertime from Stubbekøbing to Bogø island. Grønsund has several shallow areas, i.e. near Bogø, and has a strong and alternating current. Both submersed and riparian vegetation is rich, and the sound is an important breeding area for wildlife and fish. Many shore birds, including cormorants, mute swans, greylag geese, pintails, shovelers, eiders, avocets, several species of waders, as well as gulls and terns are breeding in the area. The porpoise lives in the area.