QINGDAO, Feb. 6 (Xinhua) -- Chinese scientists started their 38th ocean scientific expedition on Monday, with the country's first deep-sea manned submersible Jiaolong.
The mother ship, "Xiangyanghong 09", left east China's Qingdao carrying the sub and more than 150 personnel for a 124-day trip, the longest for Jiaolong.
The researchers will carry out surveys in the northwest Indian Ocean, the South China Sea, Yap Trench and the Mariana Trench in the west Pacific Ocean.
With Jiaolong, more discoveries are expected in the northwest Indian Ocean, said chief scientist Han Xiqiu.
The trip lasts until June 9.
Named after a mythical dragon, Jiaolong reached its deepest depth of 7,062 meters in the Mariana Trench in June 2012.
On Monday, "Hailong 2", or Sea Dragon 2, and "Qianlong 1", both unmanned submersibles, were officially deployed at the National Deep Sea Center in Qingdao.
"Hailong 2", which needs a wire to link to the support ship, can work at a maximum depth of 3,500 meters. In 2009, the home-made underwater robot discovered a deep-sea hydrothermal "chimney" vent near the equator in the eastern Pacific.
Wireless "Qianlong 1" can operate at a depth of 6,000 meters.
The three types of subs are all domestically-made and each has its own specialties, according to researchers.
A new mother ship for Jiaolong is estimated to be put into use in March 2019. It will be capable of carrying the three sub types together, said Yu Hongjun, director of the center.