China’s manned submersible, Jiaolong, completed a dive operation on April 26 in the South China Sea.

Departing from its mother ship, Xiangyanghong 09, at around 7:00 am, Jiaolong stayed underwater and conducted a dive operation for nine hours and twelve minutes before returning at around 4:19 pm.

China’s manned submersible Jiaolong begins its first dive this year in the South China Sea, south China, April 26, 2017.[Photo/Xinhua]

The submersible brought back 16 liters of sea water samples collected near the seabed to Xiangyanghong 09, alongside eight sediment samples and two rock samples. High-definition photos and video footage were also shot during the deep-water mission.

The dive on April 26 marked the first dive by Jiaolong in the second stage of China’s 38th ocean scientific expedition. The operation is set to last until May 13.

The mission witnessed a deep-dive by Jiaolong, which saw the submersible plunge 1,741 meters below sea level and spend some seven hours on the seabed.

China’s manned submersible Jiaolong begins its first dive this year in the South China Sea, South China, April 26, 2017.[Photo/Xinhua]

Three staff, including one seasoned crew member, Tang Jialing, and two interns, Liu Xiaohui and Yang Yifan, were on board the submersible.

“This was almost the longest underwater mission by Jiaolong,” said Tang.

Yang Yaomin, chief scientist for the second stage expedition, said experts had planned to choose a site for experimenting with the collection of poly-metallic nodules during the mission.

“We are working to avoid damaging the marine environment during mining operations,” said Yang. “The expedition will help develop technology for environmentally friendly deep-sea mining.”

Poly-metallic nodules are mineral resources that are generally deposited more than 4,000 meters deep beneath the sea’s surface and contain manganese, iron, copper, nickel, cobalt as well as rare earth elements.

China’s manned submersible Jiaolong begins its first dive this year in the South China Sea, South China, April 26, 2017.[Photo/Xinhua]

During the expedition, manned deep-sea submergence was also conducted in the seamount chain and continental slope areas in the South China Sea, according to scientist Shi Xuefa.

“We plan to carry out geological and biological surveys in the region,” said Shi. “The submersible will take photos of the distribution of poly-metallic nodules, deep-sea life and seafloor terrain.”

The rock samples collected from the seamount will be used in research in chronology, mineralogy and geochemistry on the South China Sea, advancing the study of the region’s structural evolution, according to Shi.

China’s manned submersible Jiaolong begins its first dive this year in the South China Sea, South China, April 26, 2017.[Photo/Xinhua]

The 38th oceanic scientific expedition started on February 6. Jiaolong completed a dive in the northwestern Indian Ocean earlier this year in the mission’s first stage. It will also conduct surveys in the Yap Trench and the Mariana Trench in the third stage.

Named after a mythical dragon, Jiaolong reached its deepest depth of 7,062 meters in the Mariana Trench in June 2012.

An oceanaut Tang Jialing enters into China’s manned submersible Jiaolong to begin its first dive this year in the South China Sea, South China, April 26, 2017. [Photo/Xinhua]

China’s manned submersible Jiaolong begins its first dive this year in the South China Sea, South China, April 26, 2017.[Photo/Xinhua]