Challenger Deep (CD) is the deepest known point in the Earth’s seabed hydrosphere. It is located in the Marianna Trench, in the Federated States of Micronesia. The depression is named after the British Royal Navy survey ships HMS Challenger (1858 – 1980), the fifth of eight ships with that name, whose expedition of 1872–1876 first located the Deep, and HMS Challenger II (1932 – 1954), whose expedition of 1950–1952 established its record-setting depth, 10 935 m below the surface. Its coordinates are at 11°22′ N 142°35′ E.
CD is a slot-shaped valley in the floor of Mariana Trench, with depths exceeding 10 850 meters. It consists of three basins, each 6 to 10 km long and 2 km wide. They are separated by mounds between the basins 200 to 300 m higher. The three basins extend about 48 km west to east if measured at the 10 650 m isobath.
The first descent by any vehicle was conducted by the United States Navy using the bathyscaphe Trieste in 1960-01-23 crewed by Swiss oceanographer Jacques Piccard (1922 – 2008) and U.S. Navy Lieutenant Don Walsh (1931 – 2023). The Trieste is currently preserved as an exhibit in the National Museum of the United States Navy in Washington, D.C. It was decommissioned in 1966 after its deep-sea explorations.
The only bathyscaphe I have seen in person is the Trieste II, a vessel designed modified by the Naval Electronics Laboratory in San Diego, California and built at the Mare Island Naval Shipyard, located on Mare Island, a peninsula part of the city of Vallejo, on San Pablo Bay in San Francisco Bay, California. It incorporated the original Terni, Italian-built sphere used in Trieste. This sphere was suspended from a new, more seaworthy and streamlined float, operating on the same principles. It was completed in 1964, then placed on board USNS Francis X. McGraw (T-AK241) and shipped, via the Panama Canal, to Boston.
Trieste II conducted dives in the vicinity of the loss site of USS Thresher (SSN-593), lost on 1963-04-10, during deep-diving tests about 350 km east of Cape Cod, Massachusetts, killing everyone on board. This lead to the implementation of a rigorous submarine safety program = SUBSAFE. Wreckage from the Thresher was found.
Between 1965-09 and 1966-05, Trieste II underwent extensive modification and conversion at Mare Island Naval Shipyard. A third reconfiguration followed resulting in the installation of a new pressure sphere, designed for operation to 6,100 m depth. She was then used as a test vehicle for the deep submergence. This resulted in the design and construction of other deep-diving submersibles which could be used in rescuing crews and recovering objects from submarines in distress below levels reachable by conventional methods.
The Trieste II was listed as equipment in the Navy inventory until 1969-09-01, when it was placed in service, with the hull number X-1. She was reclassified as a deep submergence vehicle (DSV) on 1971-06-01. The Trieste class DSV were replaced by the Alvin class DSV: more capable, more maneuverable and less fragile. After that the Trieste II was preserved as a museum ship at the Naval Undersea Museum, Keyport, Washington.
Pressure Drop
The most extensive sonar mapping of CD was undertaken by the DSSV (deep submersible support vessel) Pressure Drop, a 68.3-metre former US Navy ship. Refitted to accommodate 47 people – including 19 crew and 12 technical specialists. In previous lives it was USNS Indomitable (T-AGOS-7), a United States Navy Stalwart-class ocean surveillance ship in service from 1985 to 2002. From 2003 until 2014, she was in commission in the National Oceanic and Atmospheric Administration (NOAA) as the oceanographic research ship NOAAS McArthur II (R 330). It was then sold to Victor Vescovo’s (1966 – ) company Caladan Oceanic.
Vescovo graduated with a B.A. in Economics and Political Science from Stanford University, followed by a M.S. in Defense and Arms Control Studies from the Massachusetts Institute of Technology and a M.B.A. from Harvard Business School.
Inkfish purchased the DSSV Pressure Drop in 2022 and the crewed Deep Submersible Vehicle (DSV) Limiting Factor and was part of a package for marine research purposes. Inkfish was founded by Gabe Newell (1962 – ), a video-game developer who co-founded Valve and the digital distribution service Steam. Inkfish is a global philanthropic organization focused on marine research and innovation, known for its advanced research vessels and commitment to developing new technologies for scientific exploration. Limiting Factor has been renamed Bakunawa. The name refers to the Philippine moon dragon or moon-eating dragon, a serpent that looks like a Dragon, in Philippine mythology. It was given the designation Triton 36000/2 by its manufacturer Triton Submarines, located in Sebastian, Florida, USA.
A Norwegian Kongsberg SIMRAD EM124 multibeam echosounder system, was used to show the bottom of Challenger Deep comprised three ‘pools’ – Western, Central and Eastern.
In 2012, James Cameron became the first person to solo dive that point. Piccard, Walsh and Cameron remained the only people to reach the Challenger Deep until 2019, when regular dives in DSV Limiting Factor began. To date, 19 of the 22 successful descents have been made in the DSV Limiting Factor. No other craft has made a repeat descent. To date, there have been 27 people who have descended to the CD, the last on 2022-07-12.
My interest in deep dives began by reading about William Beebe (1877-1962). Beebe was an American naturalist, ornithologist, marine biologist, entomologist, explorer and writer. He conducted numerous expeditions for the New York Zoological Society, such as the Arcturus mission (a six-month-long research expedition in 1925 from New York to the Sargasso Sea, Cocos Island and the Galápagos Islands). He undertook deep dives in the Bathysphere, a spherical deep-sea submersible lowered into the ocean on a cable. It was used to conduct a series of dives off Nonsuch, Bermuda from 1930 to 1934. The Bathysphere was designed in 1928 and 1929 by the American engineer Otis Barton (1899 – 1992), to be used by Beebe to study undersea wildlife. Beebe and Barton conducted dives in the Bathysphere together, marking the first time that a marine biologist observed deep-sea animals in their native environment. Many of the descents made by Beebe and Barton in the Bathysphere were described by Beebe in his book, Half-Mile Down (1934). I frequently borrowed this book from New Westminster Public Library. Currently, I have an e-book edition of this book.
The bathysphere had a number of limitations. Thus, the next step was to produce a vehicle that offered independent movement. The first undertaking were made by Jacques Piccard’s, father Auguste (1884 – 1962).
Context: The father was a physicist and professor of meteorology, who first experimented with balloons. In 1931 he and Paul Kipfer (1885 – 1975) used a balloon launched in Augsburg, Germany to reach a height of 15 781 m to measure cosmic radiation. In 1932 Piccard and Belgian Max Cosyns (1906 – 1998) reached 16 940 m, starting off from Dübendorf, Switzerland. The older Piccard completed 27 balloon expeditions, ultimately reaching a height of 23 000 m. The balloon used was the FNRS 1, named after Belgian Fonds National de la Recherche Scientifique, the funding organization for the venture.
After World War II Auguste Piccard, used his experience to explore the ocean depths. In 1937 he designed the FNRS 2, built in Belgium between 1946 and 1948. It was damaged during 1948 trials in the Cape Verde Islands. It was then substantially rebuilt and greatly improved. The vessel was renamed FNRS 3 and carried out a series of descents including one to 4 000 m into the Atlantic off Dakar, Senegal, in 1954.
An improved bathyscaphe, the Trieste, was designed by Auguste Piccard and built by the Italian shipyards Acciaierie Terni and Cantieri Riuniti dell’Adriatico. It was launched in 1953, and dived to 3 150 metres that year. In 1958, the Trieste was acquired by the United States Navy, taken to California, and equipped with a new cabin designed to enable it to reach the seabed of the great oceanic trenches.
