Which feature might be marked by a buoy in navigational waters?

Buoys serve a critical role in maritime navigation by providing important information and guidance to mariners. When a buoy marks an obstruction to navigation, it signifies that there is a potential danger in the water, such as rocks, sandbars, or other hazards that could impede the safe passage of vessels. This marking alerts boaters to exercise caution and navigate accordingly to avoid collisions and ensure their safety.

In navigational waters, it is essential for buoys to clearly communicate potential hazards, as they are often placed based on the most commonly navigated routes. By designating an obstruction to navigation, mariners can make informed decisions when navigating through these waters, ensuring safe travel.

Other options, such as marking private fishing rights or locations of historical wrecks, do not align with the primary purpose of a navigational buoy, which is to provide safety and guidance for vessels. While underwater obstructions might be a concern for mariners, they are typically marked by buoys specifically meant for navigation, rather than left unmarked.