Technicians unleash China's manned deep-sea submersible, Jiaolong, June 15, 2012. China's manned deep-sea submersible, Jiaolong, made its first dive in the Mariana Trench on Friday, as part of a bid to go down as deep as 7,000 meters. The dive, which is the first of a series of scheduled six ones and began at 9 a.m. local time (2300 GMT Thursday), will attempt to reach a depth of 5,000 meters and last eight hours. (Xinhua/Luo Sha)

ABOARD XIANGYANGHONG 09, June 15 (Xinhua) -- China's manned deep-sea submersible, the Jiaolong, threw ballast iron and began to rise after reaching the depth of over-6,000 meters of the Mariana Trench on Friday.

The Jiaolong wouldn't go deeper in this dive, while it will progressively increase the depth in later five missions.

So far, the three sea drivers and the Jiaolong itself are OK.

There was something wrong with the submersible's No. 1 communication system, but the No. 2 set is working soundly.

The rise is expected to last three hours.

The dive, which began at 9 a.m. local time (2300 GMT Thursday), is the first of a series of six scheduled ones to attempt the country's deepest-ever 7,000-meter manned dive.