The film was shot at the Cherokee Nuclear Power Station outside of Gaffney, South Carolina. It had been abandoned after a local power company spent $700 million in construction. The underwater sequences were filmed in two specially constructed tanks. The first one held 7.5 million gallons of water, was 55 feet deep and 209 feet across. At the time, it was the largest fresh-water filtered tank in the world. Additional scenes were shot in the second tank which held 2.5 million gallons of water.
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