Descend to the Challenger Deep

0–200 m · Epipelagic

Sunlight zone

The top 200 metres, straight above the Challenger Deep. The descent starts here.

The ride down is a remotely operated vehicle: no one aboard, flown by pilots on the ship through its tether. Shown here as a generic work-class ROV.

• Megaptera novaeangliae, humpback whale: mothers and calves winter off Saipan
• Stenella longirostris, spinner dolphin: the dolphin most often sighted in NOAA's nearshore Mariana surveys

• Surface water: 28.7 °C
• Zone: 0–200 m

Sources: NOAA JetStream, Layers of the ocean; Reagan, J. R., et al. (2024). World Ocean Atlas 2023. NOAA National Centers for Environmental Information, Accession 0270533; Hill, M. C., et al. (2020). Found: a missing breeding ground for endangered western North Pacific humpback whales in the Mariana Archipelago. Endangered Species Research 41: 91–103 (NOAA PIFSC); NOAA PIFSC Cetacean Research Program, Mariana Archipelago small-boat surveys 2010–2019 (OBIS-SEAMAP / GBIF)

200–1,000 m · Mesopelagic

Twilight zone

The vehicle's searchlight picks out a giant squid. Architeuthis dux lives at about 200–1,000 m. The first photographs of one alive were taken at 900 m off the Ogasawara Islands in 2004, the nearest record to the Marianas.

Sperm whales hunt down here: their dives usually reach 600–1,000 m, sometimes beyond 2,000 m, and giant squid beaks turn up in their stomachs.

• Architeuthis dux, giant squid: about 200–1,000 m
• Physeter macrocephalus, sperm whale: foraging dives about 600–1,000 m
• Periphylla periphylla, helmet jelly: recorded to about 2,900 m

Sources: SeaLifeBase, Architeuthis dux (depth range 200–1,000 m); Kubodera, T., & Mori, K. (2005). First-ever observations of a live giant squid in the wild. Proc. R. Soc. B, 272, 2583–2586. doi:10.1098/rspb.2005.3158; SeaLifeBase, Periphylla periphylla (0–2,900 m, usually 0–300 m); Watwood, S. L., et al. (2006). Deep-diving foraging behaviour of sperm whales (Physeter macrocephalus). Journal of Animal Ecology 75: 814–825; NOAA Fisheries, Sperm whale species page

1,000–4,000 m · Bathypelagic

Midnight zone

No sunlight reaches this deep. The only light is made by animals.

Atolla wyvillei answers an attack with a pinwheel of blue flashes.

• Melanocetus johnsonii, humpback anglerfish: 100–4,500 m, usually 100–1,500 m
• Atolla wyvillei, alarm jelly: recorded to 1,500 m; its genus to about 5,000 m

Sources: FishBase, Melanocetus johnsonii (100–4,500 m, usually 100–1,500 m); SeaLifeBase, Atolla wyvillei (0–1,500 m); MBARI, deep-sea crown jelly (Atolla spp., 500–5,000 m; bioluminescent “burglar alarm”); NOAA Ocean Exploration, Atolla wyvillei burglar-alarm display; NOAA JetStream, Layers of the ocean

4,000–6,000 m · Abyssopelagic

The abyss

The coldest water of the whole descent is here: about 1.45–1.49 °C between 4,250 and 4,800 m. Below about 4,500 m it warms again, slightly, because compression heats the water.

Marine snow drifts down through the dark. Past the reach of the lights, sonar does the seeing.

In 2026 an expedition on this abyssal plain filmed a bigfin squid at about 5,400 m, an animal seen fewer than 100 times, and a dumbo octopus on a dive past 5,800 m.

• Magnapinna, bigfin squid: filmed at about 5,400 m, Marianas, 2026
• Grimpoteuthis, dumbo octopus: filmed on a dive past 5,800 m, Marianas, 2026

• Coldest water: ≈ 1.45 °C
• At: 4,250–4,800 m

Sources: Huang, C., et al. (2018). Scientific Reports, 8, 11791. doi:10.1038/s41598-018-30176-4; Reagan, J. R., et al. (2024). World Ocean Atlas 2023. NOAA National Centers for Environmental Information, Accession 0270533; Ocean Exploration Trust / Nautilus Live, expedition NA180: bigfin squid (Magnapinna) at about 5,400 m, 218 nmi NE of Maug, Mariana Islands (2026); Ocean Exploration Trust / Nautilus Live, expedition NA179: dumbo octopus (Grimpoteuthis) on the Mariana abyssal plain, dive past 5,800 m (2026)

Detour · 300–3,300 m

Fire under the sea

Hot vents are not on the trench floor. They sit on the arc volcanoes and the back-arc spreading ridge, from about 50 to 3,700 metres deep; the four here lie between about 300 and 3,300 m, so the story takes a detour to them.

At the Champagne vent on NW Eifuku, about 1,600 m down, droplets of liquid CO₂ rise beside 103 °C vent fluid. On Daikoku, about 410 m down, there is a pool of molten sulphur at 187 °C, black with impurities under a crust that heaves with rising gas. NW Rota-1 was the first submarine explosive eruption ever directly observed, in 2004, and ROV Jason filmed it erupting in 2006.

The deepest is Sequoia Vent, about 3,300 m down in the Hafa Adai vent field on the back-arc spreading ridge: a chimney more than 30 m tall, nearly as tall as a ten-storey building. E/V Nautilus's ROV Hercules returned to it in 2025, the first visit since its discovery nearly a decade before.

Sources: NOAA Ocean Exploration, Submarine Ring of Fire 2006; NOAA PMEL, Submarine Ring of Fire 2006: Daikoku (Sulfur Cauldron, 410 m); NOAA PMEL, NW Eifuku liquid CO₂ venting; Smithsonian Global Volcanism Program, NW Rota-1; NOAA PMEL Earth-Ocean Interactions Program, global hydrothermal vent sites list (site depths); Ocean Exploration Trust / Nautilus Live, expedition NA171: Sequoia Vent, Hafa Adai vent field, "30+ meter high" (2025); InterRidge Global Database of Active Submarine Hydrothermal Vent Fields, Hafa Adai vent field (Mariana Trough back-arc, about 3,294 m)

6,000 m and deeper · Hadal

Into the trench

These walls are built from real bathymetry of the Challenger Deep, with heights stretched about nine times so the shape reads. The trench runs about 2,550 km and averages about 70 km wide.

Pseudoliparis swirei, the Mariana snailfish, was described in 2017. It has been caught at 7,966 m and filmed at 8,178 m here. The deepest fish ever filmed, an unidentified Pseudoliparis at 8,336 m, was off Japan, in the Izu-Ogasawara Trench.

• Pseudoliparis swirei, mariana snailfish: filmed to 8,178 m

Sources: Global Multi-Resolution Topography (GMRT) Synthesis v4.5 (gaps filled from the GEBCO 2026 grid). Ryan, W. B. F., et al. (2009). Global Multi-Resolution Topography synthesis. Geochem. Geophys. Geosyst., 10, Q03014. doi:10.1029/2008GC002332; Encyclopaedia Britannica, Mariana Trench; FishBase, Pseudoliparis swirei; University of Western Australia (2023), deepest fish ever recorded

10,935 m · The Challenger Deep

The bottom

10,935 metres, give or take six. The pressure is about 1,125 bar, more than 1,100 times the surface. The water is about 2.5 °C.

Life is still here. Xenophyophores, giant single cells more than 10 cm across, have been filmed to 10,641 m in the Sirena Deep. In 2012 the cameras on James Cameron's submersible DEEPSEA CHALLENGER filmed sea cucumbers on this floor. Hirondellea gigas amphipods swarm at about 10,900 m, and can digest sunken wood.

• Hirondellea gigas, amphipod: collected at 10,897 m

• Depth: 10,935 m ± 6 m
• Pressure: ≈ 1,125 bar
• Water: ≈ 2.5 °C

Sources: Greenaway, S. F., et al. (2021). Deep-Sea Research Part I, 178, 103644. doi:10.1016/j.dsr.2021.103644; Huang, C., et al. (2018). Scientific Reports, 8, 11791. doi:10.1038/s41598-018-30176-4; Scripps Institution of Oceanography (2011), giant amoebas in the extreme deep; Gallo, N. D., Cameron, J., Hardy, K., Fryer, P., Bartlett, D. H., & Levin, L. A. (2015). Submersible- and lander-observed community patterns in the Mariana and New Britain trenches. Deep-Sea Research I, 99, 119–133. doi:10.1016/j.dsr.2014.12.012; Scripps Institution of Oceanography / UC San Diego (2013), vibrant mix of marine life found at extreme ocean depths; Kobayashi, H., et al. (2012). The hadal amphipod Hirondellea gigas possessing a unique cellulase for digesting wooden debris buried in the deepest seafloor. PLoS ONE, 7(8), e42727. doi:10.1371/journal.pone.0042727

10,898 m · 20 May 1998

The human footprint

In 1998 the remotely operated vehicle Kaikō found a plastic bag at 10,898 m.

When amphipods from six trenches were checked for microparticles such as plastic fibres, 72% had swallowed at least one. Of the ones from the Mariana Trench, every one had.

• Plastic bag: 10,898 m · 1998
• Mariana amphipods with microparticles: 100%

Sources: Chiba, S., et al. (2018). Human footprint in the abyss: 30 year records of deep-sea plastic debris. Marine Policy, 96, 204–212. doi:10.1016/j.marpol.2018.03.022; JAMSTEC DARWIN and Deep-sea Debris Database: KAIKO dive 73, cruise KR98-05, 20 May 1998 (facts cited only; no JAMSTEC imagery reused); Jamieson, A. J., et al. (2019). Royal Society Open Science. doi:10.1098/rsos.180667

1960–2022

The people who came down

Only a handful of vehicles have reached the bottom of the Challenger Deep. They are listed here, not drawn.

• 1960-01-23: Bathyscaphe Trieste, Jacques Piccard, Lt Don Walsh, 10,911 m (corrected). About 20 min on the bottom; a viewport cracked on the way down.
• 1995-03-24: ROV Kaikō, uncrewed, 10,911 m. Collected Hirondellea gigas in 1998. Lost 2003.
• 2009-05-31: HROV Nereus, uncrewed, 10,902 m. Hair-thin fibre-optic tether. Lost 2014 in the Kermadec Trench.
• 2012-03-26: Deepsea Challenger, James Cameron, solo, 10,908 m. Descent took 2 h 36 min.
• 2019-04-28: DSV Limiting Factor (Triton 36000/2), Victor Vescovo, 10,928 m reported (about 10,935 m corrected). Four Challenger Deep dives that week.
• 2020-06-07: DSV Limiting Factor, Kathy Sullivan, with Victor Vescovo. First woman, and first person to both walk in space and reach the Deep.
• 2020-11-10: Fendouzhe, Zhang Wei, Zhao Yang, Wang Zhiqiang, 10,909 m. Carried 27 scientists to hadal depths by Dec 2021.
• 2022-07-12: DSV Limiting Factor, Dawn Wright. First Black person to reach the Deep. This was Vescovo's 15th visit.

Sources: US Navy History and Heritage Command, H-Gram 041; WHOI press release, Nereus reaches the deepest part of the ocean (2009); Wikipedia, List of people who descended to Challenger Deep

For scale

Everest would fit, with 2 km to spare

Mount Everest is 8,848.86 m high. Placed in the Challenger Deep, its summit would still sit about 2,086 m below the surface.

It would not fit inside the trench, though: its rims here lie only about 3,000 to 5,000 m down, so the summit would stand 1 to 3 km above them.

Sources: Mount Everest height, 8,848.86 m (2020 Nepal–China survey, via AP); Greenaway, S. F., et al. (2021). Deep-Sea Research Part I, 178, 103644. doi:10.1016/j.dsr.2021.103644; Global Multi-Resolution Topography (GMRT) Synthesis v4.5 (gaps filled from the GEBCO 2026 grid). Ryan, W. B. F., et al. (2009). Global Multi-Resolution Topography synthesis. Geochem. Geophys. Geosyst., 10, Q03014. doi:10.1029/2008GC002332