Deepest Hole
Even though Lone Star did not find what it was searching for, its effort remained the deepest hole on the earth for another five years. Then one of the Kola boreholes, called SG-3, broke the record on June 6, 1979. And by 1983, just nine inches deep, the hole had traveled a whopping 39,000 miles through the surface of the Earth.
Technical Difficulties
With this milestone reached, scientists on the Kola Peninsula have temporarily downgraded instruments. They stopped their work on the borehole for 12 months so that different people could visit the fascinating site. However, a technical issue forced drilling to come to a halt when the experiment was restarted the following year.