What type of buoy might indicate a channel's direction and side for navigation?

The choice of lateral marks indicates a channel's direction and side for navigation, which is fundamental to safe maritime travel. Lateral marks are part of the IALA buoyage system and are specifically designed to indicate the presence of navigable channels and to guide mariners on which side to pass various navigational hazards or features. These marks use a color-coded system—typically red and green—to represent the port (left) and starboard (right) sides of the channel, respectively.

For instance, a red mark indicates the port side when entering a channel, while a green mark indicates the starboard side. The use and positioning of these lateral marks help mariners maintain a safe course and avoid potential dangers, particularly in narrow or busy waterways.

In contrast, other types of marks like special marks, safe water marks, and cardinal marks serve very different purposes. Special marks denote particular features or areas that do not fit into the normal navigational framework but require attention. Safe water marks indicate that there is navigable water surrounding them, but they do not specify channel direction. Cardinal marks provide information about safe water to the north, south, east, or west but are used to indicate safe areas in relation to another navigational point rather than channel sides.