What indicates that there is navigable water all around a mark?

Safe Water Marks indicate that there is navigable water all around the mark. These marks are typically used to signify that the water is safe for navigation in all directions. They are often placed at the entrance of harbors or in the open sea where there may be no specific hazards nearby.

Safe Water Marks are usually colored with vertical red and white stripes and are equipped with a spherical topmark or a light that helps mariners identify safe passage. Their primary purpose is to show that vessels can proceed safely in any direction from the mark, making them critical for guiding ships through navigable waterways without the risk of running aground.

In contrast, other types of marks, such as Isolated Danger Marks, indicate specific hazards that may be surrounded by navigable waters, while Cardinal Marks indicate the position of underwater hazards in relation to safe waters, thereby guiding vessels to navigate safely around such dangers.