The crossword solution for the term 'marker buoy' is DAN, which is a three-letter acronym. A marker buoy is a floating navigational aid used to mark a specific area of water, such as a channel, hazard, or shoal. It is typically a bright color and is often equipped with a light or bell to make it easier to spot. The acronym DAN stands for 'danger, anchor, navigation, ' which are the three main types of marker buoys.