Sea mark
From BAWiki
Definition
Plant as a visual mark with or without means for generating and emitting light signs, acoustic signals and radio calls or plant for generating and emitting light signs, acoustic signals and radio calls for securing and facilitating maritime traffic and the protection of the waterway and attachments to the waterway on the high seas. Note: In the sea area also: sea marks. They should be distinguished from the signs which serve the day or night designation of ships and which are given out by a watervessel.