What type of mark is used to indicate safe water according to the IALA system?

The indication of safe water within the IALA Maritime Buoyage System is specifically accomplished through the use of a safe water mark. This type of mark is designed to signify that the area surrounding it is free of hazards and provides adequate depth, making it safe for navigation. Safe water marks are characterized by their red and white vertical stripes, often topped with a spherical element. They provide a clear visual reference for mariners, confirming that the route is clear ahead in the designated navigational channel.

In contrast, can buoys, spar buoys, and cardinal marks each serve different specific functions in navigation. Can buoys typically indicate portside limits for channel navigation, while spar buoys are used to convey various information about the navigable area. Cardinal marks are specifically designed to indicate safe passage in relation to hazards and provide directions based on cardinal points (north, south, east, west). However, they do not inherently indicate that the water itself is safe for navigation, unlike the safe water mark.