Uploaded February 2017 | Updated September 2026, 6 hours ago

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What kind of technology and training do you need to dive into the twilight zone, 200-500 feet below the ocean's surface? Rebreathers, closed-circuit systems that take the place of traditional scuba tanks, allow divers to carry less air by scrubbing carbon dioxide and recirculating the oxygen from each exhaled breath. Read the full story: bit.ly/1WoKdbs

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