Obviously, if you travel north of Canada you run into the frozen wasteland of the northernmost Arctic Ocean and ultimately the geographic North Pole. Few flat earth proponents are suggesting anything different here. There are even commercial planes that fly somewhat near there on a regular basis.
If you travel due south of South America and Australia you run into Antarctica. Again, obviously. No one disputes this. The flat earth proponents suggest Antarctica is a ring around a disc with the north’s pole at the disks center. In both a globular earth and a flat earth Antarctica is south of everything. “South” is just opposite of “North”. So every where on the outer edge would be directly “South”.
This obviously creates enormous issues seeing as there is a south celestial pole above Antarctica just like Polaris is above the North Pole so south towards the southern celestial pole is not just a direction in all directions longitudinally from our geographic North Pole, but a specific location. The flat earth map does not allow for a southern axis location.
Hope that helps.
But there has been people who have circumnavigated the earth vertically. Do you have any explanations for this or is this just another "fake" thing to you guys.