SG-3 in Kola peninsula of Russia is deepest hole ever dug by man into
Earth. Its depth was 12,262 metres (40,230 ft) in 1989. It is the result
of a scientific drilling project of the Soviet Union in Kola Peninsula.
The project attempted to drill as deep as possible into the Earth's
crust. The Drilling began on 24 May 1970 and aim of drilling is to
understand the nature of the earth's crust. The result of this drilling project is known as "Kola Superdeep Borehole".