Mariana Trench Trivia
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47 free Mariana Trench trivia questions with answers — geography quiz, new questions added Sep 2026.
The Mariana Trench is the deepest place on Earth, a crescent-shaped gash in the western Pacific whose floor lies almost 11 km below the surface, more than 2 km deeper than Mount Everest is tall. This quiz starts with the basics (which ocean, how deep, where the Challenger Deep sits) and works up to the plate tectonics that made it, the pressure at the bottom, the temperature, the three basins of the Challenger Deep and the rival Sirena and Horizon deeps. It then follows the explorers: HMS Challenger's weighted rope in 1875, the echo sounders of Challenger II, the bathyscaphe Trieste and its cracked window in 1960, James Cameron's solo dive in 2012, Victor Vescovo's repeated descents in Limiting Factor, the Chinese submersible Fendouzhe and the son who followed his father to the bottom sixty years later. Life gets its turn too, from the deepest fish ever filmed to giant single-celled xenophyophores, thousands of new microbes and, sadly, plastic bags and a beer bottle. Every answer was checked against Wikipedia's articles on the Mariana Trench, the Challenger Deep and the vessels that visited them, and each question shows the sentence that supports it. Try our Pacific Ocean, oceans and Guam quizzes next.
30 of 47 questions with answers and explanations. Play the quiz
Q 01The Mariana Trench lies in which ocean?
Pacific
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.
Q 02The trench's deepest point, the Challenger Deep, takes its name from what?
A British survey ship
A British survey ship, HMS Challenger, first measured the depth there in 1875, and NASA later named a Space Shuttle after the same vessel.
Q 03Which mountain could be dropped into the trench and still have its summit about 2 km underwater?
Mount Everest
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.
Q 04On a map, the Mariana Trench traces what shape?
A crescent
A crescent: the trench bows around the Mariana Islands, and the islands curve the same way, because a single plate boundary shaped them both.
Q 05The pressure at the bottom of the trench is roughly how many times atmospheric pressure at sea level?
About 1,000
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.
Q 06How warm is the water at the very bottom of the Mariana Trench?
Just above freezing
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.
Q 07The islands that give the trench its name honour a 17th-century queen of which country?
Spain
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.
Q 08Which process, the one behind the 'Ring of Fire', formed the Mariana Trench?
Subduction
Subduction returns old seabed to the Earth's interior about as fast as new crust forms elsewhere, which is why the planet never grows.
Q 09The first sounding of the trench, made in 1875, used what piece of equipment?
A weighted rope
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.
Q 10Which technology let a 1951 expedition measure the deep far more precisely than before?
Echo sounding
Echo sounding found almost 11 km of water in 1951, nearly 3 km more than the first measurement of 1875 had suggested.
Q 11In 1960 two men sat on the floor of the Challenger Deep; how did they speak to the ship above?
By sonar telephone
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.
Q 12The Challenger Deep lies within the exclusive economic zone of which country?
Federated States of Micronesia
Federated States of Micronesia issues the permits for dives there, because the American monument named after the trench stops short of its deepest point.
Q 13In 1960 the first crewed dive to the Challenger Deep set out from a US Navy base on which island?
Guam
Q 21Japan's robot Kaikō survived the trench floor in 1995; what claimed it in 2003?
A typhoon
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.
Q 22Which film director dived to the bottom of the trench in March 2012?
James Cameron
James Cameron went down alone, the first solo dive to the deepest seabed, in a one-person sub he had helped to design.
Q 23Deepsea Challenger was built in a small workshop in which Australian city?
Sydney
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.
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.
Q 14The first people to see the floor of the Challenger Deep, in 1960, found it carpeted in what?
Soft ivory ooze
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.
Q 15Trieste, which made the first crewed descent to the bottom of the trench in 1960, was what type of vessel?
Bathyscaphe
Bathyscaphe: free of any cable, it sank 11 km, while the older bathysphere, dangling from a ship, never got a tenth as deep.
Q 16Who designed the vessel Trieste?
Auguste Piccard
Auguste Piccard, a Swiss physicist and balloonist, first sketched the idea in 1937, and his son Jacques piloted the finished craft to the bottom.
Q 17Which German steelmaker forged the crew sphere that protected Trieste's two men at the bottom of the trench?
Krupp
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.
Q 18What alarming event shook Trieste late in its 1960 descent?
An outer window pane cracked
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.
Q 19Trieste's 1960 dives were Project Nekton, a word for sea creatures that do what?
Swim freely
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.
Q 20In 1963 Trieste was used to search for which lost nuclear submarine?
USS Thresher
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.
Q 24What set Victor Vescovo's 2019 sub apart from the two crewed craft before it?
It could dive repeatedly
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.
Q 25The 2018-19 Five Deeps Expedition began at the Atlantic's deepest point, which lies in which trench?
The Puerto Rico 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.
Q 26Victor Vescovo named his submersible Limiting Factor; what did he call the support ship?
Pressure Drop
Pressure Drop, like the sub it carried, was named by its owner after a spaceship in Iain M. Banks's science fiction novels.
Q 27Which former astronaut, the first American woman to walk in space, reached the Challenger Deep in June 2020?
Kathryn Sullivan
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.
Q 28Sixty years after Don Walsh reached the bottom, which relative repeated his dive in 2020?
His son
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.
Q 29In November 2020 a crewed submersible named 'Striver' reached the trench floor; which country sent it?
China
China's Fendouzhe, whose name means 'Striver', sailed from Hainan and dived 10,909 metres, stopping just short of the deepest dive on record.
Q 30Trieste, the craft that first carried people to the trench floor, was named after what?
The city where it was built
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.