A successful dive to 7,000 meters deep by a manned submersible heralded China's ability and raised its confidence of exploring the deep ocean.

China's manned deep-sea submersible Jiaolong prepares to be put into water to make a fourth dive into the sea at the Mariana Trench on June 24, 2012. [ Photo / Xinhua ]

Jiaolong, the manned submersible named after a dragon in Chinese mythology, succeeded in reaching 7,020 meters below the surface of the sea Sunday morning in its fourth dive into the Mariana Trench.

"I was thrilled and proud," said Liu Cigui, director of the State Oceanic Administration (SOA), after the news reached Beijing.

"Breaking the 7,000-meter mark means China has obtained the capability of exploring 99.8 percent of the deep ocean with manned submersibles," Liu said. "This is a technological breakthrough."

During the Sunday operation, Jiaolong's fourth successful dive below 7,000 meters, proved that the submersible was stable in function and the performance of the team improved gradually, said the program's on-scene commander Liu Feng.

Among about 90 operational manned submersibles thoughout the world, only 12 can descend to 1,000 meters undersea and even fewer can dive deeper.

Before China's attempts, only manned submersibles of the United States, Japan, France and Russia have dived below 6,000 meters.

China started the development of Jiaolong in 2002 and its first 1,000-meter dive test was conducted in 2009.

All the designs and core technologies were developed by Chinese scientists, said Xu Qinan, chief designer of Jiaolong.

Although Jiaolong's dive was not the first or the deepest in the world, the country aimed to develop a deep sea submersible that can be stably and repeatedly be used in scientific exploration.

Compared with the sub used by renowned film director James Cameron to the bottom of the 10,898-meter-deep Mariana Trench in March, Jiaolong is not only bigger, holding three oceanauts rather than just one, but also stronger and more complicated, Xu said.

"In a bid to be applied in future scientific explorations, Jiaolong has to fulfill many dive operations, instead of just one attempt, and to overcome various landscapes on the sea bottom and do surveys," Xu said.

China planned to use the submersible in several pilot scientific explorations in next three to five years, Liu Cigui said.

"We plan to try it in our surveys in the southwest Indian Ocean and the Pacific," he said. "Also we hope to develop a team of skilled oceanauts."

China's deep-sea diving technology is an "open resource" and foreign scientists can also board the Jiaolong submersible for research, according to Liu Xincheng, an SOA official, in an earlier interview with Xinhua.

"The 7,000-meter test made us confident that our submersible can one day descend to 11,000 meters and cruise freely," said Cui Weicheng, deputy chief designer of the Jiaolong.