Following one of the most daring ocean trips ever, scientists have returned exact depth data for each of the world's five main oceans.
Data from the Five Deeps Expedition (FDE), which conducted dives from 2018 to 2019, reveals for the first time the locations of the deepest points in the Indian and Southern Oceans.
According to the data, the deepest point in the Indian Ocean is 7,187 meters deep inside the Java Trench, just off the coast of Indonesia, while the deepest point in the Southern Ocean is 7,432 meters deep within the South Sandwich Trench.
Prior to FDE, the deepest regions of certain oceans, such as the lowest point on Earth - the Challenger Deep, beneath the Mariana Trench in the Pacific Ocean - were pretty well known.
The Challenger Deep still retains the record for the deepest point on Earth, at a depth of 10,924 meters (6.8 miles), according to the expeditions.
While Brownson Deep in the Puerto Rico Trench is the deepest point in the Atlantic Ocean, it descends an astonishing 8.378 meters.
The Five Deeps Expedition was a successful 10-month effort to reach the deepest point in each of the world's five main oceans: the Atlantic, the Southern, the Indian, the Pacific, and the Arctic.
The expedition traveled 47,000 nautical miles and included 39 dives using the Limiting Factor (LV), a two-person submersible constructed by the Florida-based company Triton Submarines.
LV carried a fullocean depth multibeam echosounder of the newest generation, which sends a sequence of sound pulses to survey each region of the seabed.
A team of academics, including British Geological Survey scientists, has now released a fresh study on the mission's results in Geoscience Data Journal.
Cassandra Bongiovanni, principal hydrographic surveyor for the FDE, conducted the investigation.
'The global Five Deeps Expedition provided us with a once-in-a-lifetime chance to precisely map some of the world's most remote and deepest locations, and to confirm these depths with measurements obtained by the submersible and support landers,' she said.
'With access to cutting-edge full-ocean depth technologies, we were able to map an area similar to continental France in only 10 months.
'Around 61% of the places we visited had never been mapped using current technology.'
Prior to Five Deeps, there were significant doubts about the deepest places in the Indian and Southern Oceans.
For example, the Java Trench and the Diamantina Fracture Zone were previously considered as two candidate places for the deepest point in the Indian Ocean (DFZ).
According to FDE statistics, the Java Trench is currently the deepest point in the Indian Ocean, at 7,187 meters (4.4 miles), surpassing the DFZ's 7,019 metres.
Prior to FDE, the South Sandwich Trench, lying just north of the Antarctic continent, had not been properly studied.
The South Sandwich Trench is the world's only sub-zero hadal zone (deeper than 6,000 meters, or 20,000 feet).
The newly designated Factorian Deep, situated at the trench's southern terminus, is 7,432 metres deep.
The new data also shows that, although Meteor Deep is the deepest point in the South Sandwich Trench at 8,265 meters, it is situated within the waters of the Atlantic Ocean, therefore Factorian Deep gets the title.
This investigation also proved that the Horizon Deep beneath the Tonga Trench is the Pacific Ocean's second deepest point (at 10,816 metres).
The $35 million Triton DSV Limiting Factor - the world's only submersible capable of descending to the lowest ocean depths - was essential to the discoveries (11,000 metres, or 36,000 feet).
Limiting Factor is the first vehicle in history to have gone to the deepest point in the ocean on many occasions.
Only specialized microbes can live at such depths, which are characterized by great pressures, severe darkness, and practically freezing temperatures.
The privately sponsored exploration vehicle is designed for the deep ocean's hadal zone, which lies in V-shaped depressions at depths ranging from 20,000 to 36,000 feet.
Victor Vescovo, an American former CIA officer turned rich investor who was onboard LV for all five flights, launched FDE.
Victor Vescovo became the fourth person in history to reach Challenger Deep as part of the mission in May 2019.
Vescovo performed five dives in the Mariana Trench over the course of seven days.
Along with three new marine life species and the lowest piece of recovered mantle rock, Vescovo and his crew discovered a plastic bag and a candy wrapper, a sobering reminder of the extent of plastic pollution.