We still don't know much about some regions not that far: just think about the bottom of oceans, some caves all around, ... There is still much to discover! And

We still don't know much about some regions not that far: just think about the bottom of oceans, some caves all around, ... There is still much to discover! And for an average person, central Russia, central America, large parts of Australia, Greenland, ... are a huge mystery.