The deep-sea submersible, Jiaolong, has undergone a series of upgrades and will head to the South China Sea and the Pacific Ocean in June for a series of dives.

"Jiaolong is entering a trial period ahead of a busy schedule," said Liu Feng, director of the China National Deep Sea Center.

Liu said the first dive will be in the South China Sea in June, for scientific research, while the rest will likely be conducted in two areas in the western Pacific in July, pending approval by the International Seabed Authority for China's application to explore for cobalt-rich ferromanganese crusts.