China's unmanned submersible "Hailong 11000" dived 2,605 meters below the sea surface in the western Pacific Ocean on Sunday, succeeding in passing the 2,000 meters grade deep water test.

The submersible entered the water from its mothership Dayang Yihao (Ocean No 1), a Chinese scientific research ship, at 10:30 am Beijing time (0230 GMT) and reached the depth of 2,000 meters some 105 minutes later.

Operators conducted a system check and function test before allowing the vessel to dive deeper. It went down another 605 meters and successfully returned to the sea surface.

The unmanned, remotely-controlled submersible is designed to work at a maximum depth of 11,000 meters below the sea level. It will complete an 11,000-meter-deep sea test in three years, according to the China Ocean Mineral Resources R&D Association.

Supervisor of the operation team Cui Yunlu said that the vessel showed stable performance during Sunday's sea test, adding that the Chinese research team will choose an appropriate time to challenge the depth of 6,000 meters.

Dayang Yihao departed China's eastern port city of Qingdao on March 20, taking scientists on a 45-day scientific expedition.

Hailong literally means the Sea Dragon in Chinese.