I miss the "Inside the earth" option (in regards to the "hollow earth" - theory) in the poll (although I live on the surface of the earth).
The deepest drilling into the earth (Kola Superdeep Borehole) is "only" 12,262 metres deep - thats about only 1 % of the earth's diameter (in case the earth is a globe (I don't know)), thus far below (in average about the half of) the earth's crust.
To think the ~ 99 % (~ 44,5 % in case the ...) below us is everywhere massive is in fact also just a theory (mainly based on seismology).
No one knows for sure what's deep below us.