China's new manned submersible returned to port in Sanya, Hainan province, on Tuesday after completing its first deep-sea testing in the South China Sea.

The new submersible is called Shenhai Yongshi, meaning deep-sea warrior. It reached a depth of 4,500 meters during tests while on a 50-day expedition trip on board the science exploration ship Tansuo-1.

"It is another great achievement for China in developing deep-sea manned submersibles," said Bai Chunli, president of the Chinese Academy of Sciences, in a congratulatory letter.