When the Titan submersible, carrying five sightseers to the wreck of the Titanic, blew up thousands of metres under the ocean surface in June, it underscored why humanity knows more about the surface of some other planets than about the depths of the Earth’s oceans.
Oceans cover more than 70 percent of the earth’s surface. Yet, this underwater world is a challenging place to explore, as the Titan disaster showed. It’s a vast space. The deepest point under water, the Challenger Deep in the Pacific Ocean, is 11,000 metres deep, more than the height of Mount Everest.
