Answer: Cartography (the art of making maps) was so important in Cook's lifetime because "so much of the world was unknown" which made traveling the seas on a ship difficult because of the lack of direction. Not only this but maps gave people sailing the seas a more successful way to navigate to the places they needed to be.
Explanation: +The world was unknown, maps gave sailors a way to better navigate the ocean.
+ If there was even a small error on a map it could lead a ship tons of miles off course of where they needed to be.
Sorry if this was a bit wordy, but I hope it helps! :)