QINGDAO, June 23 (Xinhua) -- Chinese submersible Jiaolong will begin a global scientific expedition by about 2020, scientists said Friday.

The submersible, named after a mythical dragon, returned to the national deep sea center in eastern China's Qingdao Friday following a four-month deep sea tour, the country's 38th oceanic scientific expedition.

Before the 2020 expedition, China will have the submersible upgraded and finish the building of a new mothership.

The 38th expedition started in February and its completion marks the end of the submersible's five-year trial phase.

The Jiaolong is capable of diving in virtually all global seas to a depth less than 7,000 meters, scientists said.

The submersible made 30 dives during the latest expedition and descended to nearly 6,700 meters in the Yap Trench in the west Pacific, close to its record depth of 7,062 meters in 2012.

Scientists gained precious samples and data in this expedition, including rocks, large marine life, two lion fish and two unknown species.

They also reached a better understanding of deep sea hydrothermal movement in the Indian Ocean, and conducted surveys in the South China Sea that will help multi-metal nodule mining tests.