Which mile is commonly used for measurements on navigable waters?

The nautical mile is the standard unit of measurement used for navigation and maritime operations on navigable waters. This unit is particularly significant because it is based on the circumference of the Earth, specifically defined as one minute of latitude. This correlation makes it extremely useful for nautical charts and navigation, as it allows for accurate distance measurement relative to the curvature of the Earth.

Since a nautical mile is equivalent to approximately 1.15078 statute miles, it provides navigators with a consistent and universally accepted measure that remains valid regardless of changes in location. This is important for various marine operations, including charting courses, determining distances between waypoints, and ensuring safe passage through various waterways.

Other units like statute miles and land miles are primarily used on land and do not account for the unique considerations and scale of maritime navigation. River miles may refer specifically to distances along a river's bank but lack the standardization and application that a nautical mile provides in broader maritime contexts. Thus, the nautical mile is essential for effective navigation on the waters.