Ye Cong (L), pilot of the Jiaolong, and his colleagues greet onlookers prior to boarding the ship carrying the vessel in Jiangyin, Jiangsu province, July 1, 2011. [Photo by Gao Erqiang / China Daily]

Related reading: Submersible Jiaolong to dive 5km

JIANGYIN, Jiangsu - China's manned deep-diving submersible Jiaolong left Jiangyin in East China's Jiangsu province on board its mother ship Xiangyanghong 9 on Friday for a 5,000 meter dive in the Pacific Ocean between southeastern Hawaii and North America.

China is the world's fifth nation - following the United States, France, Russia and Japan - to have the technology to make a manned submersible dive at more than 3,500 meters below sea level.

Li Haiqing, a spokesman for the State Oceanic Administration, said that the dive would "take the international community by surprise".

Jiaolong, named after a mythical sea dragon, completed 17 dives in the South China Sea between May 31 and July 13 last year, reaching a maximum depth of 3,759 meters with three crew members on board.

The craft is 8.2 meters long and weighs about 22 tons.

It is designed to go to a depth of 7,000 meters, which could give China access to 99.8 percent of the ocean floor.

Jin Jiancai, secretary-general of China Ocean Mineral Resources R&D Association (COMRA), said that Jiaolong's current mission would take around 47 days, and it is expected to make four dives.

Safety would be the top priority throughout the entire mission, Jin added.

"First of all, we should bear in mind that this is a scientific experiment. Although we have studied the environment as much as possible, there are still some unpredictable conditions.

"Even if we could not reach the expected depth for some reason, we will achieve the goal of this experiment as long as all our crew members return safely to land," said Jin.

The manufacturing of Jiaolong was part of the national high technology research development plan, also known as the 863 Plan, issued in 2002. More than half of Jiaolong's parts and components were made in China.

A total of 96 experts from 13 institutions involved in the research and manufacturing of the craft were on board Xiangyanghong 9, Jiaolong's mother ship.

Xu Qinan, a researcher from the 702 Institute of China Ship Industry Corporation and Jiaolong's chief designer, said that the submersible would take about two hours to reach a depth of 5,000 meters.

A submersible is different from a submarine in that it is smaller, needs a mother ship while it is on the surface, and can go much deeper.

Jin said part of the mission is to fulfill the contract between the International Seabed Authority (ISA) and COMRA, which includes taking photographs and video footage of the sea floor, and measuring submarine topography and geomorphy, in the 75,000-square-kilometer area designated by the ISA.

"With permits from the ISA, China will be able to explore minerals and other resources for commercial purposes in this area once the technology matures," added Jin.

Jiaolong's three crew members, Tang Jialing, Fu Wentao and Ye Cong, also manned the submersible on its last dive in 2010.

Ye, Jiaolong's pilot, has been responsible for 28 of the 37 dives that it has made so far. He is also one of the designers of the craft.

In 2005, five Chinese trainee pilots and one scientist participated in eight dives in Alvin, the world's oldest most famous deep-diving craft, operated by Woods Hole Oceanographic Institution in Cape Cod, Massachusetts.

Ye was one of the five trainee pilots at the time, reported The New York Times.