Man spends billions of pounds on equipment that will look deep into and explore space and on craft that will one day take them to far distant planets in our universe and beyond,
Yet we still know so little about our own planet.
There are still parts of our jungles we have not been able to fully explore.
and 90% of our oceans still remain unexplored.
We may dig tunnels of our own, but nature has done a far better job, Aquafers and caves remain hidden below us, and due to lack of suitable technology and ability to withstand the pressures we have hardly explored any !
New caves are being found all the time, and we are going deeper and deeper.