Ripple Rock exposion in Seymour Narrows, British Columbia, 1958.This was the largest non-atomic blast ever set off at the time. It ripped out tow great mountain peaks, long a peril to ships in the inland passage to Alaska. Some 2,750,000 pounds of "Nitramex" 2H blasting agent supplied by Du Pont of Canada lifted 700,000 tons of water and rock, and ripped asunder Ripple Rock, the underwater mountain.