A daymark is a navigational aid for sailors and pilots, distinctively marked to maximize its visibility in daylight. The word is also used in a more specific, technical sense to refer to a signboard or daytime identifier that is attached to a day beacon or other aid to navigation. In that sense, a daymark conveys to the mariner during daylight hours the same significance as the aid's light or reflector does at night. Standard signboard shapes are square, triangular, and rectangular, while the standard colours are red, green, orange, yellow, and black.

Notable daymarks

Symbols used on US charts

Chart symbols used by the US National Oceanic and Atmospheric Administration Department, 2013.