The hidden underwater canyon was discovered by the seals deep under Antarctica. Click to read more. Seals wearing tracker hats discovered a hidden underwater canyon in Antarctica as part of a study led by researchers in Australia and France.
The crater dates back to 58 million years ago, instead of the previously proposed 13,000 years ago. Greenland shelters beneath its ice sheet the massive Hiawatha crater, also known as the Hiawatha impact crater or Hiawatha meteorite impact crater-which is 31 kilometers (19 miles) wide.