Also look into Mercator's letter and map to John Dee describing the in-drawing seas and whirlpool around the magnetic black mountain. This all took place in the 1500's and quite mysteriously the land at the N pole that used to appear on every map pre 1600 has disappeared over the years and we are told it is just sea ice at present. There are some connections to King Arthur and his interest in this part of the world if you dig deep.