What does a "safe water mark" indicate on a nautical chart?

A "safe water mark" on a nautical chart serves as a navigational buoy that indicates there is safe water all around it. This type of mark is typically used to denote that vessels can safely navigate in the vicinity, providing assurance that no hazards are present in that area. Safe water marks often serve as reference points for mariners to confirm their position and are essential for safe navigation in coastal areas and busy shipping channels.

They are usually depicted as a vertical red and white striped buoy with a spherical shape at the top, sometimes accompanied by a light or other signaling mechanism to improve visibility. By recognizing these marks, mariners can effectively plan their routes while avoiding potential dangers associated with navigational hazards, shallow waters, or underwater obstructions elsewhere in the area.