50 Fun Facts About Mariana Trench

The Mariana Trench lies in which ocean?

It sits about 200 km east of the Mariana Islands in the western part of the ocean.

The Challenger Deep, the trench's deepest point, is a small slot-shaped valley at which end?

It lies about 10,935 metres down, some 300 km south-west of Guam.

The bottom of the trench is more than 2 km farther from sea level than the summit of which mountain?

If Everest were dropped into the trench, its peak would still be more than a mile underwater.

Roughly how long is the crescent-shaped Mariana Trench?

It averages about 69 km wide.

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

That is 1,086 bar, or about eight tons per square inch.

What is the water temperature at the bottom of the Mariana Trench?

Just above freezing, and utterly dark.

The islands that give the trench its name were christened Las Marianas after a 17th-century queen of which country?

The queen was Mariana of Austria, second wife of Philip IV of Spain, which is why Austria is a tempting wrong answer.

The trench forms where the ocean floor to its east is thrust beneath which smaller plate?

The Pacific crust there is up to 170 million years old, cool and dense, which is why it sinks so deep.

The Mariana Islands themselves are volcanic, formed by what process?

Water trapped in the sinking Pacific plate lowers the melting point of the mantle above it.

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

The rope recorded 8,184 metres; the deep was later named for HMS Challenger and HMS Challenger II.

Which technology let Challenger II measure the deep far more precisely in 1951?

It recorded 10,900 metres at the spot now called the Challenger Deep.

The Soviet vessel Vityaz reported a depth of 11,034 m in 1957 at a spot it called what?

The figure has not been confirmed by later surveys.

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

The US Mariana Trench Marine National Monument, created in 2009, covers only the parts inside American waters.

What is the closest land to the Challenger Deep, about 287 km to the south-west?

It is one of the outer islands of Yap; Guam lies 304 km to the north-east.

The Challenger Deep is made up of how many basins arranged from west to east?

Each is 6 to 10 km long and about 2 km wide, separated by mounds 200 to 300 metres high.

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

It carried Jacques Piccard and Don Walsh, and used iron shot for ballast and petrol for buoyancy.

Who designed the vessel Trieste?

The Swiss scientist was the father of pilot Jacques Piccard; the US Navy bought the craft in 1958 for $267,000.

How long did Trieste take to descend to the bottom in 1960?

It sank at less than a metre per second, and the ascent took 3 hours 15 minutes.

What alarming event happened to Trieste as it passed 9,000 metres?

The Plexiglas pane shook the whole vessel, but the crew pressed on to the bottom.

The 1960 Trieste dive was the final goal of which US Navy programme?

The series of dives was conducted in the Pacific near Guam.

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

It found wreckage 2,560 metres down off New England and earned a Navy Unit Commendation.

Which Japanese remotely operated vehicle reached the deepest part of the trench in 1995?

It set a diving record of 10,911 metres and collected mud samples in 1996 that turned out to contain living organisms.

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

He piloted the Deepsea Challenger to 10,908 metres in the fourth-ever descent.

Deepsea Challenger was built in which city?

Engineer Ron Allum, a cave diver, invented a syntactic foam called Isofloat that made up 70% of the craft's volume.

Deepsea Challenger's syntactic foam replaced what flotation method used by Trieste?

The foam is made of tiny hollow glass spheres set in epoxy resin.

Who set a record 10,928 m descent in April 2019 and first dived the Challenger Deep more than once?

He dived four times in a week in the DSV Limiting Factor, a Triton 36000/2 submersible.

Vescovo's Five Deeps Expedition of 2018-19 set out to reach the bottom of every what?

He had already completed the Explorers Grand Slam of both poles and the Seven Summits.

Vescovo's submersible was called Limiting Factor; what was its support ship named?

The pairing was reported to cost about US$50 million including three robotic landers.

Which former astronaut dived to the Challenger Deep with Vescovo on 7 June 2020?

The former NOAA administrator descended to the Eastern Pool.

Kelly Walsh dived to the Challenger Deep in 2020, following his father, who reached the bottom in which year?

Sixty years after his father, he spent four hours on the bottom of the Western Pool.

The Chinese submersible that reached the bottom of the trench in November 2020 is named what?

It reached 10,909 metres and returned in 2024 for 23 dives.

As of 2022, how many crewed descents to the bottom of the trench had been made?

There had also been seven uncrewed descents.

Who became the first Black woman to explore the Mariana Trench, in July 2022?

As mission specialist she used side-scan sonar to map the Western Pool.

The 1960 Trieste crew reported a flatfish on the seabed. What do many biologists think it was?

Fish are not thought to survive below about 8,500 metres because of the pressure.

Giant single-celled xenophyophores found in the trench in 2011 belong to which group?

They are the largest known cells, over 10 cm across, and can withstand heavy metals; one was found at a record 10.6 km down.

The Mariana snailfish, filmed at 8,178 metres in 2017, is named after whom?

Pseudoliparis swirei has transparent skin, incomplete bones and probably no sight.

The theoretical maximum depth at which fish can live is thought to be about how far down?

Only the Mariana snailfish and the undescribed 'ethereal snailfish' have been recorded below 8,000 metres.

The huge amphipods filmed in the trench in 2014 are an example of what phenomenon?

The 'supergiants' grow far larger than their shallow-water relatives.

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.

A 2016 study of trench crustaceans found extremely high levels of which banned pollutant?

Later work found every amphipod sampled had swallowed microplastics.

What piece of rubbish was observed in the Challenger Deep's Western Pool in 2024?

Vescovo had already found a plastic bag and sweet wrappers on the bottom in 2019.

The Sirena Deep, the ocean's third-deepest known spot, was named for a mapping research group from which US state?

It was found in 1997 by Hawaii Mapping Research Group scientists surveying near Guam and measures 10,714 metres.

How long did Piccard and Walsh spend on the ocean floor during Trieste's 1960 dive?

The cabin temperature was 7 °C, and to their surprise they regained sonar contact with the support ship USS Wandank at maximum depth.

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

Two conical hoppers fore and aft of the crew sphere each held 9 metric tons of it, while gasoline-filled tanks provided buoyancy.

In which year did the US Navy purchase the bathyscaphe Trieste?

Before that it had made 48 Mediterranean dives deeper than 3,700 metres as the Batiscafo Trieste between 1953 and 1957.

Which Australian engineer headed construction of James Cameron's Deepsea Challenger?

Working from a small workshop in Leichhardt, Sydney, he created the Isofloat syntactic foam that let thrusters be mounted without a steel skeleton.

How long did Deepsea Challenger take to reach the seafloor in 2012, almost twice as fast as Trieste?

A Rolex strapped to the sub's robotic arm kept working throughout, though hydraulic problems hampered the sampling equipment.

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

The sub had been donated to Woods Hole Oceanographic Institution and was heading to Baltimore for shipment back to Australia on loan.

Which US president established the Mariana Trench Marine National Monument in 2009?

It protects 246,610 square km of the Mariana Archipelago, though the Challenger Deep itself lies just outside the monument.

The hybrid ROV Nereus, which reached the Challenger Deep in 2009, was lost in 2014 where?

It was diving at 9,900 metres when it was lost; in 2009 it had streamed live video during a 27.8-hour mission across the eastern basin.