A lateral buoy is used in maritime navigation to indicate the edges of a navigable channel. This type of buoy provides critical information to mariners, helping them to safely navigate through water ways by marking the sides of the channel. Lateral buoys follow a specific system of colors and markings; typically, a red buoy marks the right side of the channel when entering from the sea, while a green buoy marks the left side. This system helps to convey important navigational information and ensures that vessels can travel through channels without running aground or straying into shallow waters.
Other options, such as indicating permanent anchorage points, dangerous underwater terrain, or rest areas for mariners, do not correctly describe the function of lateral buoys. Instead, these options relate to different types of navigation aids or markers used to convey specific safety information, but not the primary purpose of lateral buoys. Understanding the distinctive roles of buoys is essential for safe navigation and efficient maritime operation.