However, women have to overcome many obstacles to become oceanauts, said Liu Xincheng, deputy director of the North China Sea Branch of State Oceanic Administration. Because the space in Jiaolong, China's manned submersible, is very small, only big enough for three people to sit together, going to the toilet can be difficult for women during a dive of more than 10 hours.

Fu, the 30-year-old oceanaut, took an empty bottle for long dives on the Jiaolong to urinate in. Bottles and paper nappies are used by oceanauts in a submersible instead of a toilet.

"It will be inconvenient for female oceanauts during long dives because there is no bathroom on board," Fu said.

Unlike the Shenzhou IX spacecraft, on which astronauts had separate sleeping areas and bathrooms, Jiaolong, which is 8.2 meters long and 3.4 meters high, only has enough space for three people to sit.

"From getting on board to coming out, you can stay in there for at least 12 hours, which poses great difficulties, physically and mentally," Fu said, adding that oceanauts do not drink water the night before a dive.

Cui Weicheng, deputy commander of the 7,000-meter dive project and Jiaolong co-designer, said a person's sex is not an obstacle for oceanaut selection, saying once on board, there are no men and women — just oceanauts and scientists. China now has three oceanauts — Ye Cong, Tang Jialing and Fu Wentao, all male.

In 2006, China began selecting oceanauts. The requirements are as tough as those for astronauts. An oceanaut must be familiar with the structure, equipment and control of a submersible. Until now oceanauts were required to be men, under 35 years of age and with a bachelor degree or above in shipbuilding, machinery or electronics. They also had to pass a rigorous physical exam.

As more oceanauts are expected to pursue a career in deep-sea diving, the country is also investing in new facilities for deep-sea exploration.

The construction of a new National Deep Sea Center is expected to begin in Qingdao, Shandong province, this year. With an estimated cost of 495 million yuan ($78 million), the center will provide technical support for the country's deep-sea exploration and development, said Liu Baohua, center director.

In June, China's manned submersible, Jiaolong, set a new national dive record after reaching 7,062 meters below sea level during its fifth dive into the Mariana Trench in the western Pacific Ocean.

In order to better use the submersible, Liu Feng said a 4,000-ton support ship will be built before 2015 and another manned submersible with a designed depth of 4,500 meters is also under construction.