China’s polar research team has completed the country’s first-ever cooperative operation of deep-sea manned submersibles of Jiaolong and Fendouzhe and returned to port on Monday.

During the 98-day expedition, the team operated in the Arctic Ocean for 56 days, navigating 1,989 nautical miles through ice-covered waters and conducting a series of scientific investigations and experiments. Its work included 43 dive missions using the Fendouzhe and China’s first dive in the Arctic by the Jiaolong team.

The collaborative effort cultivated a specialized polar deep-diving research team, making China the only nation worldwide to conduct continuous manned submersible operations in Arctic dense ice zones.