Well, if not all the way to it, then they've certainly gotten very close. But there are monsters that live far out the deepest parts of the oceans, and it's dangerous to go if you aren't sure where it is you're heading to. And of course, there are always people who go off looking for the Land of the Green Isles and things like that, but those sorts of expeditions are usually never heard from again, so.

[She watches this explanation closely, trying to imagine a ball big enough to hold a whole world of people without any of them slipping off down the side--not an easy prospect.]

You really mean to say that your whole world moves around that way? My goodness, do you have to tie everything down to keep it from breaking as it goes?