Developed by Florida submarine manufacturer Triton, but with much of the engineering work taking place here in the UK, the vessel was piloted to a record-breaking depth of 10,928m by US financier and explorer Victor Vescovo.
The dive is part of the wider so-called Five Deeps Mission, an effort to take a manned submersible to the deepest points of the world’s five oceans, which has been hailed as an unprecedented opportunity to study the deep, dark trenches of the 6,000-11,000m Hadal Zone.
During the visit to the Mariana Trench, the team reportedly discovered a number of new species, including four types of crustaceans known as amphipods. It also detected sweet wrappers and a plastic bag: depressing evidence of the scale of the oceans' plastic pollution problem.
The project has already visited the Puerto Rico Trench in the Southern Ocean (8,376m), the Atlantic’s South Sandwich Trench (7433m) and the deepest part of the Java Trench in the Indian Ocean (7,192m).
The latest dive reached a greater depth than either of the previous manned visits to the trench, including James Cameron’s 2012 Deepsea Challenger mission (10,908m) and the US Navy’s 1960 mission using the Trieste “bathyscape” which held the record of 10,912m until the latest achievement.
Unlike these earlier efforts, which only descended to the bottom of Challenger Deep once, Vescovo’s vessel, dubbed the “Limiting Factor”, completed four dives to the bottom of Challenger Deep and one final dive on May 7, 2019, to the Sirena Deep which is also in the Mariana Trench, approximately 128 miles to the northeast.
As previously reported by The Engineer, building a submarine able to endure the phenomenal pressures experienced at these depths required some extreme engineering solutions: including the development of a giant precision-engineered titanium pressure hull able to withstand 16,000psi.
Powered by specially engineered lithium-polymer batteries and propelled by 10 powerful electric thrusters, the vessel has been carefully engineered with safety in mind. For instance, all of its thrusters, batteries and manipulators are ejectable meaning the pilot can rapidly increase the buoyancy of the sub and also disentangle it should it become snagged on something.
Commenting on the mission's latest milestone Vescovo said: “This submarine and its mother ship, along with its extraordinarily talented expedition team, took marine technology to an unprecedented new level by diving – rapidly and repeatedly – into the deepest, harshest area of the ocean. We feel like we have just created, validated, and opened a powerful door to discover and visit any place, any time, in the ocean – which is 90 per cent unexplored.”
The next stop is the Horizon Deep within the Tonga Trench in the South Pacific Ocean, before the team head for the Arctic Ocean to carry out the expedition’s fifth and final dive.