text: That all depends on what theory you believe. The current theory is that you can go approximately 25 miles down before you hit magma ( that's melted rock in case you don't know ).  Not a good idea, but you may not even get close enough before the intense heat kills you, or you may have some kind of cave in. \nAnother theory is the "Hollow Earth" theory. Supposedly the Earth is more like a shell and great deal inside is hollow, with entrances both at the North and South Poles. There are websites that explain more on this. If this is true, you would dig so many miles in before you go to the great cavern and fall towards the other side.