What happened to the sub when it disappeared beneath the icy depths?

Strange structures up to 1,300 feet (around 400 metres) long have been discovered deep beneath the ice in Antarctica. The never-before-seen shapes were uncovered when a remotely operated vehicle (ROV) ...

A whopping 300 water canyons have been discovered by researchers across Antarctica - some reaching the depths of 4,000 meters (13,123 feet). All thanks to new high-resolution bathymetric data, ...