What are the advantages and disadvantages of the mercator projection?

Advantages:

The two properties, conformality and straight rhumb lines, make this projection uniquely suited to marine navigation: courses and bearings are measured using wind roses or protractors, and the corresponding directions are easily transferred from point to point, on the map, with the help of a parallel ruler or a pair of navigational protractor triangles.

Disadvantages:

Mercator projection distorts the size of objects as the latitude increases from the Equator to the poles, where the scale becomes infinite. So, for example, Greenland and Antarctica appear much larger relative to land masses near the equator than they actually are.

The advantages are that it is good for naval crossings  and preserves the shapes.