Gerardus Mercator was a pretty influential cartographer. In fact, when most people think of a map of the world, they think of Mercator's projection (for better or worse). One of Mercator's accomplishments was his 1595 posthumously published atlas, Atlantis pars altera.
As you would expect from a map from 1595 there are some major issues. His northern America has no connection with reality, Greenland is smaller, and an island (Frisland) has appeared between Iceland and Greenland. What is most interesting his his depiction of the geographic north pole and his two magnetic north poles. The below is Mercator describing the geographic north pole and one of the magnetic north poles.
In the midst of the four countries is a Whirl-pool . . . into which there empty these four indrawing Seas which divide the North. And the water rushes round and descends into the earth just as if one were pouring it through a filter funnel. It is four degrees wide on every side of the Pole, that is to say eight degrees altogether. Except that right under the Pole there lies a bare rock in the midst of the Sea. Its circumference is almost 33 French miles, and it is all of magnetic stoneMercator's other magnetic north pole is located in the present day Chukchi Sea north of the Bering Strait.
Map Information
Septentrionalium Terrarum descriptio from Atlantis pars altera. Mercator, Gerhard. 1595.
