Landfall Mark (or Buoy)
The first mark (or buoy) seen by an observer approaching the land from the open sea.
It usually serves to indicate the seaward approach to a harbour, river or estuary.
Note: In the U.S.A. this is also sometimes called a Sea-Buoy.
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM