BEIJING — China made several breakthroughs in deep sea exploration as a team sailed 7,929 nautical miles to explore the trenches in the west Pacific Ocean, the Chinese Academy of Sciences (CAS) said on March 23.

The 68-day expedition made China the first to obtain 10,000-meter-deep artificial seismic profile data with a domestic ocean bottom seismograph, at the Challenger Deep in the Mariana Trench, the CAS said in a statement.

The team returned to Sanya in South China’s Hainan province on March 23.

The Challenger Deep at around 11,000 meters in the Mariana Trench is the deepest part of the ocean.

Haiyi, China’s domestic underwater glider, reached a record depth of 6,329 meters in the Mariana Trench.

During the trip, submersible Haidou dived to over 10,000 meters five times. It reached the sea bottom at a depth of 10,886 meters, the first time China has conducted unmanned navigation and video transmission at over 10,000 meters.

The expedition team also sampled snailfish in the Yap Trench at a depth of 7,884 meters, the maximum depth where China has sampled fish.