GUANGZHOU, April 28 -- China's first self-designed deep-sea exploration vessel, Haiyang Liuhao, left the port city of Guangzhou on Tuesday for research in the Pacific Ocean.

The vessel, on its fifth research expedition since being delivered for use in October 2009, set off at 10 a.m. with 130 researchers on board and carrying unmanned submersible Haima. It is due to return in the middle of November, according to China's marine geological authorities.

Haiyang Liuhao, also known as Ocean No. 6, will use advanced technology to collect samples and measure microtopography near the sea bed.

This will be the first time that Haima, which can dive to 4,500 meters via remote control, has explored deep sea resources in the Pacific Ocean.

Haiyang Liuhao finished its last research expedition in November after a 162-day exploration of the Pacific Ocean.