Mikara was anchored on the NE coast of the island of Falster in the approach to the Gronsund between Falster and Bogo. Reasonable shelter from NW to SE. I wanted to check our position relative to an unlit buoy and flashed a powerful white torch towards the buoy. It immediately lit up in brilliant green. At time, didn't know whether this was unique to the area or to Denmark but subsequently found same in Varberg in Sweden.