To commemorate the achievement, China Post issued a souvenir cover Sunday. (Compiled by Dong Feng)

The submersible Shenhai Yongshi (Deep Sea Warrior) sails back Sunday to Sanya in south China's Hainan Province after the oceanic research vessel TS10 carried out the country's first deep sea archaeological mission. (Photos: VCG)

The mission lasted 121 days covering 17,000 nautical miles in the southwest Indian Ocean and the central Indian Ocean for the first time.

Since November 10, 2018, the Deep Sea Warrior manned submersible operated 62 times, with the average water operating time at 9 hours and 15 minutes, creating a number of records in China's manned deep diving history.