One of the world’s largest man-made caves is deep inside Mount DuBose. The Kemano Powerhouse is an underground cavern 85 feet wide, 135 feet high and 700 feet long. The tunnel or hole to the Powerhouse is 1,000 feet long, 85 feet wide, and 100 feet high and once contained twenty thousand truckloads of rock. The world's largest underground power station was "secure against landslides and air raids." (National Geographic, 1956)
Eight turbine generators were lowered into place. The Powerhouse generators were estimated to produce a continuous output of 1,250,000 kilowatts, and required an installed capacity of 1,750,000, over three times the capacity of all BC in 1937. By 1956, Kitimat Works would be consuming about 35 percent of all the electric energy generated in BC that year.
Expansion was planned for the future – lengthening the powerhouse by another 400 feet, with additional generators, and an ultimate capacity of 2,400,000 horsepower.