What limitation is noted for the Mercator projection regarding distance measurements?

The Mercator projection is a cylindrical map projection that significantly distorts sizes and distances, particularly as one moves away from the equator. As the latitude increases, the scale of the projection becomes exaggerated, leading to a situation where distances are misrepresented at higher latitudes.

For example, Greenland appears much larger than it actually is when compared to its size relative to countries near the equator. Thus, while the Mercator projection does allow for the accurate representation of direction (making it useful for navigation), it compromises distance accuracy, especially above about 60 degrees latitude. This is why the statement related to higher latitudes is essential in understanding the practical limitations of the Mercator projection when used for distance measurements.