Answer:
Hi! The answer(s) would be, travel, funding, material, navigation, and nature.
Step-by-step explanation:
Travel-
Geographers in the early times would need a transportation method to travel where they need to go. Yachts, pontoons, and speed boats weren't around back then. They would have to use a small canoe, ship, or kayak.
Funding-
They would need money to expedite across the world, of course. In 2020, money is easy to come by but back in 1632 or 1937, it would have to be earned.
Material-
Methods of transportation require materials. I could imagine if a group of explorers would expedite across the world to explore the globe they'd use a large ship. It would take about more than a year to gather materials and build the boat.
Navigation-
Explorers couldn't use maps back then, because they were in the making. Finding landmarks while in the middle of the ocean would surely be treacherous.
Nature-
Bears, wolves, coyotes, pumas, and many more predators would be roaming the soon to be explored territory. Not to mention the mountains and caves they would have to find.
(This is considerate in the earlier years, instead of 2020.)
Hope this helped!