47 Fun Facts About Mariana Trench

The Mariana Trench lies in which ocean?

Pacific: most of the world's deepest trenches ring this one ocean, because its old, heavy seabed is sinking back into the Earth around the edges.

The trench's deepest point, the Challenger Deep, takes its name from what?

A British survey ship, HMS Challenger, first measured the depth there in 1875, and NASA later named a Space Shuttle after the same vessel.

Which mountain could be dropped into the trench and still have its summit about 2 km underwater?

Mount Everest would vanish with room to spare. A fitting fate: the rock near its summit is limestone laid down on an ancient seabed and later pushed up to the roof of the world.

On a map, the Mariana Trench traces what shape?

A crescent: the trench bows around the Mariana Islands, and the islands curve the same way, because a single plate boundary shaped them both.

The pressure at the bottom of the trench is roughly how many times atmospheric pressure at sea level?

About 1,000 times: pressure climbs by one atmosphere for every 10 metres of seawater, and nearly 11 km of it is stacked above the trench floor.

How warm is the water at the very bottom of the Mariana Trench?

Just above freezing, at 1 to 4 °C, yet a touch warmer than the water higher up, because the enormous pressure squeezes the water and heats it slightly.

The islands that give the trench its name honour a 17th-century queen of which country?

Spain's queen regent Mariana of Austria was honoured in 1668, when the islands shed their older Spanish name, Islas de los Ladrones, the Islands of Thieves.

Which process, the one behind the 'Ring of Fire', formed the Mariana Trench?

Subduction returns old seabed to the Earth's interior about as fast as new crust forms elsewhere, which is why the planet never grows.

The first sounding of the trench, made in 1875, used what piece of equipment?

A weighted rope, lowered as a routine sounding, ran out to 8,184 metres, by far the deepest of the voyage, so the astonished crew repeated the measurement to be sure.

Which technology let a 1951 expedition measure the deep far more precisely than before?

Echo sounding found almost 11 km of water in 1951, nearly 3 km more than the first measurement of 1875 had suggested.

In 1960 two men sat on the floor of the Challenger Deep; how did they speak to the ship above?

By sonar telephone: their voices travelled as sound through 11 km of water, with no wires and no radio, the first conversation between the surface and the deepest seabed.

The Challenger Deep lies within the exclusive economic zone of which country?

Federated States of Micronesia issues the permits for dives there, because the American monument named after the trench stops short of its deepest point.

In 1960 the first crewed dive to the Challenger Deep set out from a US Navy base on which island?

Guam lies about 320 km north-east of the deep, and a Navy tug needed four days to tow the diving craft out to the spot through heavy seas.

The first people to see the floor of the Challenger Deep, in 1960, found it carpeted in what?

Soft ivory ooze, as fine as talc, covered the floor: the glassy skeletons of tiny algae that died near the surface and drifted down for 11 km.

Trieste, which made the first crewed descent to the bottom of the trench in 1960, was what type of vessel?

Bathyscaphe: free of any cable, it sank 11 km, while the older bathysphere, dangling from a ship, never got a tenth as deep.

Who designed the vessel Trieste?

Auguste Piccard, a Swiss physicist and balloonist, first sketched the idea in 1937, and his son Jacques piloted the finished craft to the bottom.

Which German steelmaker forged the crew sphere that protected Trieste's two men at the bottom of the trench?

Krupp forged the thick steel ball after the US Navy took over the craft and ordered a stronger cabin, built to survive the deepest spot on Earth.

What alarming event shook Trieste late in its 1960 descent?

An outer window pane cracked with a bang that shook the cabin, but the crew kept going and only spotted the damage once they were on the bottom.

Trieste's 1960 dives were Project Nekton, a word for sea creatures that do what?

Swim freely: nekton swim where they choose while plankton drift, a name that suited a craft moving on its own rather than hanging from a ship's cable.

In 1963 Trieste was used to search for which lost nuclear submarine?

USS Thresher had sunk off Cape Cod that April with all hands; Trieste found its debris, including the sail still marked with the hull number 593.

Japan's robot Kaikō survived the trench floor in 1995; what claimed it in 2003?

A typhoon snapped the cable tying it to its ship off Shikoku, and the vehicle that had survived the deepest seabed on Earth was never recovered.

Which film director dived to the bottom of the trench in March 2012?

James Cameron went down alone, the first solo dive to the deepest seabed, in a one-person sub he had helped to design.

Deepsea Challenger was built in a small workshop in which Australian city?

Sydney housed the workshop where the sub took shape, with parts such as its thrusters built by hand because nothing off the shelf could survive the depth.

What set Victor Vescovo's 2019 sub apart from the two crewed craft before it?

It could dive repeatedly: each earlier crewed craft touched the bottom once and never went back, while this one made five trips to the trench floor on one expedition.

The 2018-19 Five Deeps Expedition began at the Atlantic's deepest point, which lies in which trench?

The Puerto Rico Trench, 8,376 m down, was stop one of five as a single sub set out to touch the lowest point of every ocean.

Victor Vescovo named his submersible Limiting Factor; what did he call the support ship?

Pressure Drop, like the sub it carried, was named by its owner after a spaceship in Iain M. Banks's science fiction novels.

Which former astronaut, the first American woman to walk in space, reached the Challenger Deep in June 2020?

Kathryn Sullivan had barely surfaced when she and her pilot phoned the astronauts aboard the International Space Station, comparing notes between the ocean floor and orbit.

Sixty years after Don Walsh reached the bottom, which relative repeated his dive in 2020?

His son, Kelly Walsh, went down to the very basin his father had visited, the first time anyone had been back to that spot in sixty years.

In November 2020 a crewed submersible named 'Striver' reached the trench floor; which country sent it?

China's Fendouzhe, whose name means 'Striver', sailed from Hainan and dived 10,909 metres, stopping just short of the deepest dive on record.

Trieste, the craft that first carried people to the trench floor, was named after what?

The city where it was built: the designer was invited to the Italian port of Trieste in 1952, and a shipyard there made the hull.

Which American oceanographer became the first Black woman to reach the Challenger Deep, in July 2022?

Dawn Wright, a specialist in mapping the seabed, used the dive to test a prototype scanner built to keep working at any ocean depth.

The 1960 Trieste crew reported seeing a flatfish on the seabed; what do many biologists now think it was?

A sea cucumber is the usual suspect: such animals do live on the deepest seabed, while no fish has ever been found within two kilometres of it.

Fist-sized xenophyophores live in the trench, yet each one is what?

A single cell, among the largest known: each is roomy enough that worms and other small sea creatures make their homes on and inside it.

What role does the small, pink, see-through Mariana snailfish play in the trench 8 km down?

The top predator: with no larger hunters at that depth, the snailfish gorges on tiny crustaceans and looks active and well fed.

Snailfish thrive 8 km down, so why do scientists think no fish can survive on the trench floor?

Pressure ruins proteins: fish pack their cells with a protective chemical to cope, and by roughly 8 km down they are carrying as much as they can.

How do amphipods filmed deep in the trench differ from their shallow-water relatives?

Far larger: amphipods are normally 2-3 cm long, but the 'supergiants' filmed in the trench can reach 30 cm, a pattern called deep-sea gigantism.

The deepest ocean zone, from about 6 to 11 km down, is named after which Greek god?

The hadal zone exists only in trenches, covering less than 0.25% of the seafloor.

Crustaceans from the trench floor carry sky-high levels of which banned chemical, once common in electrical insulation?

PCBs were banned in the 1970s but barely break down; the trench animals carried fifty times more than crabs from one of China's most polluted rivers.

What piece of rubbish greeted the crew of a 2022 dive on touching down in the Challenger Deep?

A beer bottle was among the first things the crew saw, nearly 11 km down; a plastic bag and sweet wrappers had already turned up there in 2019.

Before island schoolchildren renamed it in 2009, the Sirena Deep bore the name of a mapping research group from which US state?

Hawaii: the Hawaii Mapping Research Group found the hole in 1997 and lent it their initials, until students renamed it after a girl turned half fish in a Guam folk tale.

After a descent of nearly five hours, how long did Trieste's crew stay on the trench floor in 1960?

Twenty minutes was all: an outer window had cracked on the way down, so the two men cut their stay short and headed back up.

What did Trieste use as ballast to sink, releasing it again to rise?

Iron shot sat in two hoppers, held in by electromagnets, so even a total power failure would let it pour out and send the craft safely back up.

What liquid rises in droplets from a vent on Eifuku volcano, near the trench?

Liquid carbon dioxide: the droplets rise like fizz, which is why the site is nicknamed the Champagne vent.

What design feature let Deepsea Challenger reach the seabed in about half the time Trieste took?

A hull that dives upright let it fall fast, but a hydraulic leak then smeared oil across the viewport, so its pilot left after about three hours instead of the planned six.

What happened to Deepsea Challenger while being hauled along Interstate 95 in Connecticut in 2015?

The truck caught fire, probably when its brakes failed and set the rear tyres alight; a craft that had shrugged off the deepest seabed was badly scorched on a motorway.

Which US president created the Mariana Trench Marine National Monument, one of three he signed in a day?

George W. Bush signed all three marine monuments on 6 January 2009, a parting act just two weeks before he left office.

The robot sub Nereus reached the Challenger Deep in 2009; what destroyed it in another Pacific trench in 2014?

The water pressure crushed part of the craft about 10 km down in the Kermadec Trench; the crew knew it was gone when debris floated to the surface.