Three unmanned deep sea landing facilities descended over 10,000 meters underwater and completed sea tests in the world deepest Mariana Trench in the Pacific.

Workers release a deep sea landing facility at the world deepest Mariana Trench in the Pacific. [Photo / CCTV.com]

Cui Weicheng, director of Hadal Life Science Research Center at Shanghai Ocean University, led a team of researchers to carry out research at the Challenger Deep project in the Mariana Trench.

The group left Dec. 3 on Zhangjian, a research vessel and mothership of the Rainbow Fish series, and included three deep-sea landing devices, one unmanned search submersible and a manned submersible, all capable of diving 10,000 meters.

From Dec. 25 to 27, three deep-sea landing devices descended into the trench.

The first Rainbow Fish landing device took photographs, the second took sediment samples and the third took biological samples, Cui said.

All three submersibles reached over 10,000 meters, and the third device brought back 103 amphipods, he said.

The Rainbow Fish project is a mobile lab co-funded by the state and private capital.