BEIJING - The hatch of the Jiaolong, a Chinese-manned submersible vessel, opened at 10:13 am on Tuesday (Beijing time) in international waters in the Pacific Ocean.

That was about four hours after a test dive had taken the craft to 5,057 meters below sea level.

The dive, which began at 3:38 am, was a complete success, the State Oceanic Administration said.

Going into the depths with the vessel were three crew members: Ye Cong, Yang Bo and Fu Wentao.

That Jiaolong can travel to such a depth means it is capable of reaching more than 70 percent of the seabeds in the world, said Wang Fei, deputy director of the oceanic administration and head of the lead team in the diving test program.

"This will pave the way for a record-breaking 7,000-meter test dive in 2012," Wang said.

Japan now holds the record for sending a vessel on a deep dive. That country's Shinkai 6500 dove 6,527 meters into the depths in August 1989.

"The purpose of this test program was to learn if there are problems with the Jiaolong and to improve it constantly," Wang said.

Deep dives especially test a submersible vessel's ability to withstand strong pressure and to remain watertight, according to Wang.

"At a depth of 5,000 meters, the Jiaolong withstood pressure that amounted to 5,000 tons per square meter," Wang said.

In less than a year, the Jiaolong has undergone work to improve its operating system, insulation monitoring system and video system.

Deep diving, meanwhile, is not only a test for the vessel but also the crew onboard, who must work underwater continuously for six to eight hours, Wang said.

Having tasted success from the recent mission, the team behind the Jiaolong is preparing to send the vessel on another 5,000-meter dive at an unspecified later date. The mission the next time calls for both scientific research and further testing of the craft's various functions, said Wang Fei.

The Jiaolong is the first manned submersible vessel in the world that was designed to travel to 7,000 meters below sea level, according to Xu Qinan, chief designer of the submersible.

Xu said the Jiaolong's equipment is state of the art and its underwater communications systems and undersea propulsion systems allow the craft to "move back and forth easily under the sea."

The Chinese-built Jiaolong, named after a mythical sea dragon, has gone on several deep dives in recent days. On Thursday, it traveled to a depth of 4,027 meters with three people aboard. But a plan to take the craft to 5,000 meters below sea level on Friday was scuttled because sea conditions were then unfavorable.

From May 31 to July 18, 2010, the craft completed 17 dives into the South China Sea. On the deepest, the craft went to 3,759 meters below sea level with three crew members on board.

China, which initiated the Jiaolong project in 2002, is the fifth country to send a man 3,500 meters below sea level, following the United States, France, Russia and Japan in that regard.