出典:Wiktionary
出典:Wikipedia
出典:『Wikipedia』 (2011/02/17 23:02 UTC 版)
A daymark or a day marker is a structure such as a tower constructed on land as an aid to navigation by sailors. While similar in concept to a lighthouse, a daymark does not have a light and so is usually only visible during daylight hours. Some disused lighthouses remain useful by serving as daymarks.