Which 2018-2019 expedition visited the deepest points of all five oceans?

The 2018–2019 expedition that visited the deepest points of all five oceans was the Five Deeps Expedition.

Led by explorer Victor Vescovo, the mission aimed to reach and scientifically survey the deepest location in each ocean. Its crewed submersible, DSV Limiting Factor, reached the Puerto Rico Trench in the Atlantic, the South Sandwich Trench in the Southern Ocean, the Sunda or Java Trench in the Indian Ocean, Challenger Deep in the Pacific, and Molloy Deep in the Arctic.

The expedition began in December 2018 and completed its final major descent on 24 August 2019, ahead of its original September target. It covered roughly 47,000 miles and included 39 submersible dives, along with extensive mapping and lander deployments.

A common mix-up is confusing the expedition with the Challenger Expedition, the 1872–1876 scientific voyage that explored and surveyed large areas of the world’s oceans. The Five Deeps Expedition was a modern, focused effort to reach the deepest point in all five recognized oceans.