China's first female pilot trainee dived on Saturday as copilot with deep-sea manned submersible Jiaolong, China's first such sub, in the southwest Indian Ocean.

Zhang Yi, 27, was in charge of communicating with the sub's support ship, operating the camera and observing obstacles through the left window during the dive.

"I piloted Jiaolong in testing pool last year and it was very cool," Zhang said prior to the dive, "I think it will be more exciting to dive in ocean and I have been looking forward to this dive for months."

In this dive, Jiaolong was expected to collect some samples of rocks, sulfide, hydrothermal fluid and living beings in this hydrothermal area, said Yu Hongjun, chief commander of the expedition.

"Today Jiaolong is going to dive in hydrothermal area, where topography and environment are very complicated, so I think I will learn a lot from the pilot, Tang Jialing," said Zhang, who graduated with a master's degree in engineering last summer.

China recruited six pilot trainees for deep-sea manned sub out of 130 candidates in 2013 and two of the six are female. The other female pilot trainee is Zhao Shengya, who is scheduled to make her first dive with Jiaolong in a week.

The six trainees will be qualified to pilot deep-sea manned sub after a two-year-training, according to Yu.

For the time being, China has two pilots of deep-sea manned sub, Tang and Fu Wentao, who were recruited in 2007.

Being on a 120-day expedition, Jiaolong will conduct 20 dives to research polymetallic sulfides, biological diversity, hydrothermal microbes and genetic resources in the southwest Indian Ocean.