Scientists put trackers on Antarctic seals to help them map the ocean floor. The deep-diving seals revealed a massive underwater canyon over a mile deep. This canyon may help scientists predict how the Antarctic ice sheet will react to climate change. Joseph MarlowUnderstanding ocean geography helps scientists predict how Antarctica's ice sheet has reacted to global climate change in the past. Antarctic seals, like the 50 Weddell seals and 215 southern elephant seals they tagged, regularly travel to great depths of the ocean.

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Persons: Clive McMahon, aren't, they're, Joseph Marlow, Fausto Ferraccioli Organizations: Service, Sydney Institute of Marine Science, East, NBC, Australian Center for Excellence, Aquatic, Seals, Australian Antarctic Program Locations: Vincennes Bay, Antarctica