All 33 Miners Rescued, 2010 Copiapó Mining Accident, Chile

Exploratory bore holes
Percussion drills (rotary hammer drills) were used to make 6 boreholes about 5.5 inches (15 centimeters) wide to find the miners. The rescue effort was complicated by out--date maps and several boreholes drifting f-target because notoriously hard rock that exacerbated the drill's tendency to drift. On 19 August, one the probes reached the area where the miners were believed to be trapped but found no signs life.