Kola Superdeep Borehole

The Kola Superdeep Borehole SG-3 on the Kola Peninsula reached a true vertical depth of 12,262 m in 1989. It remains the record depth for a vertical scientific borehole, although some deviated oil and gas wells have longer measured paths along their trajectories. The comparison is therefore about depth below the surface, not total length along a slanted well.