Jiaolong, China’s manned submersible, completed a dive Wednesday in the South China Sea.

Departing its mother ship Xiangyanghong 09 at around 7 a.m., Jiaolong stayed underwater for nine hours and twelve minutes for the dive before returning at around 4:19 p.m.

It managed to bring 16 liters of sea water samples collected near the seabed, eight sediment samples and two rock samples back to Xiangyanghong 09, in addition to high-definition photos and video footage shot during the mission.

Wednesday’s dive marks the first dive by Jiaolong in the second stage of China’s 38th ocean scientific expedition, which will last until May 13.

The maximum depth of the Jiaolong mission on Wednesday was 1,741 meters below sea level, and the submersible spent some seven hours on the seabed.

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

“This is almost Jiaolong’s longest underwater mission,” said Tang.

In an interview with Xinhua prior to the drive, Yang Yaomin, chief scientist for the second stage expedition, said experts had planned to choose a site for experimenting with the collection of polymetallic nodules during the mission.

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

Polymetallic 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.

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 polymetallic 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.

The 38th oceanic scientific expedition started on Feb. 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.

Archaeologists announced Wednesday neolithic ruins dating back 4,500 to 5,000 years had been found in southwest China’s Sichuan Province.

The ruins was found on Ling Mountain in the ancient city of Langzhong last July, when villagers were building a reservoir, said Sun Zhibin, from the Sichuan Provincial Cultural Relics and Archaeology Research Institute.

A team led by Sun excavated the ruins from September 2016 to January 2017.

A total of 108 items were found at the ruins, including porcelain pots and plates, and stone tools, such as axes and spears.

“The discovery has provided new material for the research on cultural blending in the Sichuan Basin and its surrounding culture,” he said.

The discovery, the first ruins dating back to the late neolithic period near the middle reaches of Jialing River, has put back human activity at Langzhong from 3,000 years ago to 4,500 to 5,000 years ago, said Sun.

China will increase research on smog in its battle against air pollution in Beijing and surrounding areas.

Government agencies, including environmental protection authority, academies and institutions will work together to integrate resources, according to reports of a State Council executive meeting presided over by Premier Li Keqiang on Wednesday.

Scientists working on anti-smog research may be given extra funding from the central budget.

The work will focus on causes of the heavy seasonal air pollution, emission control and health.

The government hopes to improve air quality and explore transferable pollution control systems for all parts if the country which suffer from smog.

China is addressing air pollution with stricter measures on emissions and an emphasis on clean energy. Minister of Environmental Protection Chen Jining said earlier this week that Chinese cities reported more “good air” days in 2016.

Three tourists are being investigated for causing damage to a valuable tourist spot in eastern China’s Jiangxi Province, local authorities said.

The suspects from neighboring Zhejiang Province drill holes in a 128-meter-tall rock on Sanqingshan Mountain, a world natural heritage site, and used ropes to climb to the top of the rock on April 15, according to the site’s administration committee. They also refused to listen to staff guidance at the site.

The rock, known as the “Giant Python of the Mountain,” is of scientific and aesthetic significance after more than 300 million years of geological evolution, but has poor stability and is only 7 meters in diameter at the thinnest part.

Geological experts found that the rock had sustained damage from the tourists’ drilling.

Further investigation is underway.

China launched its second aircraft carrier Wednesday morning in northeast China’s Dalian shipyard in Liaoning Province.

The new carrier, the first domestically-built one, was transferred from dry dock into the water at a launch ceremony that started at about 9 a.m. in Dalian shipyard of the China Shipbuilding Industry Corp.

It is China’s second aircraft carrier, which comes after the Liaoning, a refitted former Soviet Union-made carrier that was put into commission in the Chinese People’s Liberation Army Navy in 2012.