World's largest canyon could be hidden under Antarctic ice sheet: A previously unknown canyon is thought to be over 1,000 kilometres long and in places as much as a kilometre deep, which would make it comparable in depth to the Grand Canyon in United States, but many times longer.

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World's largest canyon could be hidden under Antarctic ice sheet: A previously unknown canyon is thought to be over 1,000 kilometres long and in places as much as a kilometre deep, which would make it comparable in depth to the Grand Canyon in United States, but many times longer.