Plenty of ships have completely circumnavigated Antarctica, so it isn't the edge of the world. So far nobody in the FES knows where the edge is. Or, if not an edge, where "The Forbidden Zone", the Great Boundary Line, the No-Go Barrier --- whatever you want to call it -- is. Makes it very tough to insist that the Earth is flat if one can continuously sail or fly from one place to another and the mileage or fuel consumption or travel time shows it's consistent with a globe, not a flat plane.