Earth is an ocean planet, with over 70 percent of its surface covered in seas. With deep-sea robots, scientists regularly reveal new insights into the most mysterious realms of these expansive waters.

is one of China’s vessels for exploring deep waters. The ocean floor is shaping up to be the next theater of global resource competition. (Zhang Jinggang/Imaginechina/AP) Warning: This graphic ...

It looked like a shadow at first — but after several minutes, a rare species of deep-sea shark had swum by an underwater camera 54 times, delighting researchers. The Miami Herald reported on the ...