Timeline of Trench Discoveries

The HADES program represents a culmination of a more than 100 years of hadal and deep-ocean trench exploration and discovery. Two sampling campaigns in the 1950s (the Danish Galathea and the Soviet Vitjaz expeditions) form the basis of much of our knowledge of hadal ecosystems, followed by multiple opportunistic observations in the years and decades following these expeditions. Far from being devoid of life as originally perceived, the hadal zone is now thought to host a substantial diversity and abundance of fauna. Below we provide a timeline of discovery for deep-ocean trenches. Scroll through the links at the bottom of the screen to explore the history of this exploration and discovery– from 1895 to the present.

1895-05-01 00:00:00

Depth of Kermadec recorded

British expedition on the HMS Penguin recorded a depth of 5155 fathoms (9144 m) in the Kermadec Trench in the Southwest Pacific Ocean.

1899-01-01 00:00:00

Tonga Trench is trawled

The US RV Albatross trawled at 7632 m in the Tonga trench, but like the Challenger samples, only fragments of a siliceous sponge were recovered, again placing doubt on the origin of the animal (Agassiz and Mayer 1902).

1901-03-01 00:00:00

Deepest fish found

The first fish from hadal depths was sampled by the Princess Alice in the eastern Atlantic Ocean. This cusk eel, Bassogigas profundissimus, held the “deepest fish” record at 6035 m.

1948-08-17 00:00:00

Swedish Expedition

Swedish expedition on the Albatross successfully trawled a variety of benthic species from 7625-7900 m from the Puerto Rico Trench (Nybelin, 1951). The catch comprised mostly holothurians (with some polychaetes and isopods) and unequivocally proved that life existed well beyond 6000 m (Eliason, 1951; Madsen, 1955; Nordenstamm, 1955).

1949-05-31 19:33:18

Soviet Vitjaz expeditions

Two research campaigns on the Soviet Vitjaz expeditions (1949-1953, 1954-1959) sample mutliple hadal trenches

1950-01-01 00:00:00

Phillipine trench measured

USS Cape Johnson during World War II at 5740 fathoms (10,500 m) in the Philippine trench off Mindanao, which was for years thought the deepest place on Earth (Hess & Buell 1950).

1951-01-01 00:00:00

Danish Expedition

Anton Bruun and Danish research vessel Galathea recovered sea anemones and amphipods, isopods, bivalves, and holothurians from 10,190 meters in the Philippine Trench. By the end of the cruise they had trawled in five trenches and collected more than 115 species at depths greater than 6000 meters. Total of 65 grab samples. The Galathea also collected five liparids (snailfish) of the species Careproctus kermadecensis (Nielsen 1964) in one haul between 6660 m and 6770 m in the Kermadec Trench.

1951-01-01 00:00:00

Term 'subduction' coined

The disappearance of crust beneath another was termed ‘subduction’ (Amstutz 1951)

1953-01-01 00:00:00

Soviet Expedition

Two additional liparid species were sampled by bottom trawling during the Soviet Vityaz expeditions (1953–1957) in the northwestern Pacific Ocean: an individual Careproctus amblystomopsis from 7230 m in the Kuril-Kamchatka Trench; and a species of Careproctus, from 7579 m in the Japan Trench. Capture of benthic animals from 10.6 km in the Tonga Trench and 10.7 km in the Marianas Trench.

1954-01-01 00:00:00

Horizon Deep named

Scripps vessel, RV Horizon, recorded 5814 fathoms (10,633 m) in the Tonga Trench (SE Pacific Ocean) and coined the site Horizon Deep (Fisher 1954).

1955-01-01 00:00:00

Ultra-Abyssal zone named

Russian coin the deep trench ecosystem as the ‘Ultra-abyssal zone; based on a biological transition at 6000-7000 m (Zenkevitch et al 1955). The definition of a trench was defined as ‘a long but narrow depression of the deep-sea floor having relatively steep sides’ (Wiseman and Ovey 1953) with ‘features such as a flat floor’ (Menzies and George 1967), area of ‘high seismic activity’ (Ewing and Heezen 1955) and ‘negative gravity anomalies’ (Worzel and Ewing 1954).

1956-01-01 00:00:00

Hadal zone named

Anton Bruun first described depths in excess of 6 km as a unique ecological realm: the hadal zone.

1960-01-23 00:00:00

Deepest Dive by man

Jacques Piccard and Don Walsh reached the deepest point on the ocean floor (10,912 meters at the bottom of the Challenger Deep, Marianas Trench) in the bathyscaphe Trieste.

1960-11-24 07:47:06

The Hadal Community published

Torben Wolff publishes ‘The Hadal Community: An Introduction’ in Deep-Sea Research (Wolff 1960).

1962-01-01 07:47:06

AMerican PROA expedition

The American PROA expedition on the Spencer F. Baird obtained ~4000 images of the hadal seafloor from depths of 6758 to 8930 m in the Palau, New Britain, South Solomon and New Hebrides trenches (Lemche et al 1976).

1962-04-01 10:27:45

Deepest Polychaete Record

The record for the deepest polychaete species held by Poecilochaetus vityazi collected at a depth of 10,687 meters from the Tonga Trench.

1964-05-24 00:00:00

French Archimède dives Puerto RIco Trench

The French Archimède bathyscaphe observed 200 small fish similar to Careproctus species (family: Liparidae) and three individuals belonging to two other fish species in the Puerto Rico Trench at 7300 m.

1965-01-01 07:47:06

plate tectonics official

The official acceptance of plate tectonics (originally coined ‘New Global Tectonics’) by the scientific community occurred at a symposium at the Royal Society of London in 1965 quickly followed by a complete model based on 6 major plates and their relative motions (Le Pichon 1968).

1968-01-01 10:27:45

Mesoplankton Study Published

Vinogradov published a study on the vertical distribution of mesoplankton in the Mariana Trench, Bougainville Trench, Kermadec Trench and Kurile-Kamchatka Trench.

1970-01-01 10:27:45

Deepest Fish Collected

A specimen of fish Abyssobrotula galathea (Nielsen 1977) was collected at 8370 m in the Puerto Rico Trench. This specimen was considered to be the deepest-living fish ever collected.

1972-12-25 14:32:06

first recorded evidence of live hadal fauna

American SOUTHTOW expedition to the Peru-Chile Trench deployed a free-fall camera 17 times between 84 and 7023 m which provided the first recorded evidence of live hadal fauna (described in Hessler et al 1978).

1975-01-01 10:27:45

Deepest Samples Collected

Two deepest samples (presumed Foraminifera and meiofauna) were collected from a grab sample taken at 9807 meters from the floor of the Philippine Trench by R. R. Hessler from Scripps Institution of Oceanography during a cruise on the Research vessel Washington.

1976-01-01 10:27:45

First quantitative samples

First quantitative sample from hadal regions including meiofauna with macrofauna was taken by Jumars and Hessler at 7200 min the Aleutian Trench.

1978-12-25 14:32:06

scavenging amphipods

large densities of scavenging amphipods photographed using a lander system on the RV Thomas Washington, at 9600 and 9800 m on the floor of the Philippine Trench (Hessler et al 1978).

1979-01-01 10:27:45

Brownson Deep Sampled

George and Higgins sampled the Brownson Deep in the Puerto Rico Trench at 8560 meters and reported 17 specimens in a 62 µm mesh.

1979-12-23 09:42:18

Gilliss Expedition

RV James M. Gilliss successfully obtained two trawls from 7600 and 8800 m and two box cores from 8560 and 8580 m in the Puerto-Rico Trench (George & Higgins 1979).

1979-12-25 14:32:06

Vitjaz completes last cruise

Vitjaz completed her last cruise in 1979 and returned to the port of Kalininigrad which she had left 34 years before. It is currently a maritime museum, residing on the banks of the River Pregolya in Kaliningrad.

1980-12-25 14:32:06

Live amphipods recovered

Hyperbaric traps are used to recover live amphipods from the trenches under ambient pressures (Yayanos 2009)

1985-01-01 10:27:45

Deepsea Clams discovered

During a series of dives of the submersible Nautile, colonies of vesicomyid clams, Calyptogena phaseoliformis (Métivier et al.,1986), were discovered from the Japan Trench (5,650–6,000 m depth) and the Kurile Trench (5,100–5,800 m depth).

1985-06-01 10:27:45

Chemosynthetic Communities discovered in Japan Trench

The Shinkai 6500 and the ROV Kaiko, revealed the bathymetric zonation of the chemosynthetic communities in the deepest part of the landward slope of the Japan Trench.

1989-06-01 10:27:45

hadal region endemic species data published

Data published by Belyaev showed that of more than 600 species collected at hadal depths, 56% were endemic to hadal regions.

1995-12-29 04:50:42

ROV Kaiko is built

The construction of the first full ocean depth rated remotely operated vehicle (ROV) Kaiko (Kyo et al 1995; Mikagawa & Aoki 2001). The ROV descended to 10,911 m and placed a plaque bearing the name and date of the dive to officially mark the deepest point on Earth.

1997-01-01 10:27:45

Barophillic Bacteria isolated from Challenger Deep

Two strains of obligately barophilic bacteria were isolated from a sample of the world’s deepest sediment, from ROV Kaiko in the Mariana Trench, Challenger Deep, at a depth of 10,898 m.

1999-01-01 10:27:45

deepest chemosynthetic community found

The deepest chemosynthetic community in the world was discovered by the Japanese ROV Kaiko from the Japan Trench (40°03–04′ N, 144°17′E: 7,330–7,430 m depth). The community is dominated by a thyasirid clam.

2002-12-29 04:50:42

full ocean depth ctd scans

Full ocean depth CTD cats and near bottom current measured between 9 and 10km m in the Marianas Trench and the Izu-Bonin Trench (Taira et al 2005, 2004; Taira 2006).

2003-12-29 04:50:42

ROV Kaiko Lost

ROV Kaiko accidentally lost off Shikoku Island in an emergency ascent during typhoon Chan-Hom (Momma et al 2004; Tashiro et al 2004; Watanbe et al 2004).

2005-01-01 10:27:45

amphipods documented

The first account of the structure and vertical zonation of the scavenging amphipod of the Tonga and Kermadec Trenches (Blakenship 2006) using baited free-vehicle traps at depths between 5155 and 10,787 m.

2006-12-29 04:50:42


Beginning of HADEEP projects, a collaboration between the Universities of Aberdeen (UK) and Tokyo (Japan)

2007-01-29 04:50:42


UNESCO proposes that the deep-sea benthic biogeographic classification depth ranges are; upper bathyal (300-800 m), lower bathyal (800-3500 m), abyssal (3500-6500 m) and hadal (6500-11,000 m) (UNESCO 2009), reducing the hadal transition by 500m.

2007-12-29 04:50:42

live hadal fish observed

First observations of live hadal fish made in the Kermadec and Japan trenches (Jamieson et al 2009)

2007-12-29 04:50:42

ROV/Crawler ‘ABISMO’

New ROV/Crawler ‘ABISMO’ reaches 9760 m in the Izu-Ogasawara trench and 10257 m in the Mariana Trench where small sediment and water sampled were obtained (Itoh et al 2008; Yoshida et al 2009).

2008-09-30 10:27:45

First images of living fish recorded in hadal zone

A free-fall baited lander, Hadal-Lander A was deployed in the Japan Trench at 7703 m from the Japanese research vessel Hakuho-Maru completing the deepest known in situ observations of a hadal sanilfish (Pseudoliaris amblystomopsis). A baited video lander deployed in the Kermadec Trench, Tonga Trench and the Japan Trench and 5469m in the Marianas region (NW Pacific) discovered the Benthesicymid prawn Benthesicymus crenatus, a crustacean of the order Decapoda never found before in the hadal zone. Using baited camera landers, the first images of living fishes were recorded in the hadal zone (6000–11 000 m) in the Kermadec and Tonga Trenches, and the Japan and Marianas Trenches.

2009-05-31 10:27:45

Nereus dives to Mariana Trench

The HROV Nereus successfully completed its first dive to the hadal ocean depth of 10,903 m at 11_22.1’N, 142_35.4’E in the Mariana Trench. Bait-attending fauna of the Kermadec Trench (4329-7966 meters) was investigated using a baited camera and trap lander, revealing typical scavenging fish communities and natantian decapods. A total of 813 invertebrates were collected. The Census of Marine Life provides records of all polychaete species collected below 2000 meters. A total of 3633 records were assembled into a database, revealing that 768 species, 358 of which were new to science, have been reported from the deep sea over the past 200 years.

2010-10-22 20:20:06

trench connection

‘Trench Connection’, First international symposium of hadal biology and ecology held in Tokyo, Japan (Jamieson and Fujii 2011)

2012-03-26 04:38:48


James Cameron piloted the DEEPSEA CHALLENGER nearly 11 kilometers (over 6 miles) beneath the surface to Challenger Deep, the deepest spot in the global ocean.

2012-12-04 00:00:00


The HADES group met in Wellington, New Zealand and announced a call for microbiologists and meiofaunal biologists to join the team.

2013-04-22 21:28:56


One year after the record-setting trip, Cameron transferred the DEEP SEA CHALLENGER submersible to WHOI as part of a partnership aimed at advancing ocean science and exploration.

Timeline of Trench Discoveries

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