This photo taken on Dec 18, 2014 shows Zhang Yi (L) and another female pilot Zhang Shengya. [Photo/Xinhua]

Her first dive lasted a total of 11 hours, and involved such tasks as gathering samples of deep-sea rocks and creatures, seeking hydrothermal areas, and testing the temperature of the hydrothermal fluids.

Two other professionals joined Zhang in her first attempt, including a veteran scientist who took part in the dives years ago to test the capability of the submersible.

Shortly after she entered the cabin, the scientist told her that they were going to spend a day without swaying, because the vessel would turn stable once it entered the water, Zhang said.

During the eight hours spent in the deep ocean, the crew members had no time to eat or rest.

"It's either working or searching for the next spot. We race against the clock because it is not easy to dive to such a length," she said.

With a diameter of 2.1 meters, the submersible was packed with all kinds of equipment and oxygen cylinders, and all the three members had to crouch in the narrow cabin.

And because there is no bathroom on board, female pilots have a urine collection bag and use a curtain to get some privacy.

When describing what the view is like from the sea surface, the woman said it's totally dark, and the visibility is only six to seven meters after turning on the submersible's light.

"We saw some creatures, such as shrimp, crabs and fish, around hydrothermal areas, and hydrothermal fluids kept spewing out, like an outbreak of volcano," she said.

"Our life on board is not that boring as some people assume," she said, adding that time flies as the crew works underwater or maintains the vessel ashore.

Jiaolong would go ashore near Mauritius every month to get replenished during the expedition, she said.

Jiaolong works well under the water, because all its functions have been sharpened during the 10 years since its creation, she added.