Workers transport China's manned submersible Jiaolong to its mother ship the "Xiangyanghong 09" scientific exploration ship in Jiangyin, east China's Jiangsu Province, May 31, 2012. The Jiaolong would challenge a 7,000-meter dive to the Mariana Trench on June 3. (Xinhua/Chen Jian)

In March, Hollywood director James Cameron used a specially designed submarine to become the first man to travel solo to the depths of the Mariana Trench. He reached 10,898 meters and stayed for about three hours before he began his return to the surface, the National Geographic Society reported.

However, unlike Cameron's dive, "Jiaolong will do more scientific research while underwater, and each dive may last up to 10 hours," Liu Xincheng, deputy director of the State Oceanic Administration's North China Sea branch, told China Daily.

"If the planned dive is successful, China will hold the record for performing the deepest dive, surpassing Japan, whose Shinkai 6500 dove 6,527 meters in August 1989," he said.

In 2010, Jiaolong reached a depth of 3,759 meters, making China the fifth country to acquire deep-diving technology capable of passing the 3,500-meter mark. The other countries are the United States, France, Russia and Japan.

In July, the vessel dived 5,188 meters below sea level in the Pacific Ocean, which effectively means China can conduct scientific surveys in 70 percent of the world's seabed areas.

During this month's mission, the three technicians on board will be checking for problems in the submersible's ability to withstand strong pressure and to remain watertight, Liu said.

"Several improvements have been made both to Jiaolong and its mother ship, including the operating and video systems," chief designer Xu Qinan was quoted as saying by Xinhua News Agency on Sunday.

He said GPS devices have also been fitted on Xiangyanghong 09 to monitor the submersible underwater.

High pressure will be the greatest challenge for Jiaolong when it attempts to dive 7,000 meters. Underwater, pressure increases at the rate of one atmosphere for every 10 meters in depth. One atmosphere is equal to about 10 metric tons of force per square meter.

The deep-sea dive will also test the crew, Fu Wentao, one of the three hydronauts, told Xinhua, "but we're full of confidence. All of us have passed physical training and several underwater simulations."

According to the State Oceanic Administration, China is working hard to build a new mother ship that will take deep-sea vessels to sites, as well as a vessel that can conduct scientific research in oceans.

Scientists say the ocean floor contains rich deposits of a range of potentially valuable minerals, but the extreme depths pose obstacles.