A diver enters the diving bell to conduct 300-meter saturation dive under the South China Sea, Jan. 9, 2014. China succeeded in its first 300-meter saturation dive in the morning on Jan. 12 as three divers returned safe and sound from deep water to the living chamber on their ship. The diving bell actually reached a depth of 313.5 meters under the South China Sea. Saturation diving technology enables human beings to withstand high water pressure by saturating human tissue with inert gas. Photo:Xinhua

China succeeded in its first 300-meter saturation dive on Sunday morning as three divers returned safe and sound from deep water to their ship.

The diving bell reached a depth of 313.5 meters under the South China Sea, according to Guo Jie, chief director of the experiment.

The three divers, Hu Jian, Guan Meng and Dong Meng returned to the deck of the ship at 5:09 am on Sunday.

Saturation diving technology enables human beings to withstand high water pressure by saturating human tissue with inert gas, Guo explained.

The technology allows divers to stay at deeper sea levels than conventional techniques.

Three other Chinese divers, Li Hongjian, Luo Xiaoming and Tan Hui, began another attempted saturation dive at 8 am on Sunday and were due to return to the ship at about 2 pm. The divers will stay in a chamber until January 24 to let the inert gas in their tissue return to normal pressure, said Shen Hao, director of the Shanghai rescue and salvage center.

China is now working to develop saturation diving technology that would work at a depth of 500 meters, said Wang Zhenliang, director of the China Rescue and Salvage Center of the Ministry of Transport.

To date, eight countries, namely Britain, the US, Switzerland, Norway, France, Germany, Japan, Russia, have succeeded in 400-meter saturation dives, according to Wang.

The US and France are in a leading position in saturation diving technology, according to Guo.

"Today's success indicates that China's saturation diving development has outpaced India," said Guo.

It is commonly used in deep sea exploration, in rescue operations at sea and in engineering construction at the bottom of the sea.

China had previously only conducted such experiments in laboratories. Chinese divers once reached 493 meters in a simulation, according to lab records.

Construction of the 300-meter saturation dive system began in November 2007, when the Shanghai Salvage Bureau signed a construction contract with a Scotland-based diving and subsea equipment producer.

Guo said that a locally developed saturation dive system took divers to 103.5 meters under the South China Sea on a rescue mission in November 2006.

China has made impressive achievements in marine research in recent years. In 2012, the Jiaolong, China's most advanced manned submersible, achieved a record dive depth of over 7,000 meters.

Industry insiders expect China to become the world's largest diving market in the coming years as the sector has reached the saturation point elsewhere.