Even though we live on planet Earth, a huge part of it is a mystery to humans.We’ve only mapped about 25 percent of the sea floor, but a recent push by NASA’s Surface Water and Ocean ...

But parts of the stricken submersible will probably be left on the ocean floor indefinitely, they said. It remained unclear whether any human remains were seen or could be retrieved.

The four assistants, along with several others, carried underwater video cameras and dived to parts of the ocean floor off Australia’s southern coast that scientists had never seen before.