TIL about Sebastian Münster's 1540 map of the Americas, the first one to show that North and South America were connected by an isthmus and the first to call it 'The New World.'
As it should be... Navigators could determine latitudes pretty accurately by using astronomy. It was the longitude that was a big problem (maybe that's part of the reason Japan is placed in the middle of the Pacific).
There was a British miniseries about John Harrison, the clockmaker who figured out how to measure longitude, with Jeremy Irons and Michael Gambon. Worth watching if you can find it or want to watch the shitty quality versions on YouTube.