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50 free Mariana Trench trivia questions with answers — geography quiz, new questions added Aug 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 50 questions with answers and explanations. Play the quiz
Q 01The Mariana Trench lies in which ocean?
Pacific
It sits about 200 km east of the Mariana Islands in the western part of the ocean.
Q 02The Challenger Deep, the trench's deepest point, is a small slot-shaped valley at which end?
Southern
It lies about 10,935 metres down, some 300 km south-west of Guam.
Q 03The bottom of the trench is more than 2 km farther from sea level than the summit of which mountain?
Mount Everest
If Everest were dropped into the trench, its peak would still be more than a mile underwater.
Q 04Roughly how long is the crescent-shaped Mariana Trench?
2,550 km
It averages about 69 km wide.
Q 05The pressure at the bottom of the trench is roughly how many times atmospheric pressure at sea level?
About 1,000
That is 1,086 bar, or about eight tons per square inch.
Q 06What is the water temperature at the bottom of the Mariana Trench?
1 to 4 °C
Just above freezing, and utterly dark.
Q 07The islands that give the trench its name were christened Las Marianas after a 17th-century queen of which country?
Spain
The queen was Mariana of Austria, second wife of Philip IV of Spain, which is why Austria is a tempting wrong answer.
Q 08The trench forms where the ocean floor to its east is thrust beneath which smaller plate?
Mariana
The Pacific crust there is up to 170 million years old, cool and dense, which is why it sinks so deep.
Q 09The Mariana Islands themselves are volcanic, formed by what process?
Flux melting
Water trapped in the sinking Pacific plate lowers the melting point of the mantle above it.
Q 10The first sounding of the trench, made in 1875, used what piece of equipment?
A weighted rope
The rope recorded 8,184 metres; the deep was later named for HMS Challenger and HMS Challenger II.
Q 11Which technology let Challenger II measure the deep far more precisely in 1951?
Echo sounding
It recorded 10,900 metres at the spot now called the Challenger Deep.
Q 12The Soviet vessel Vityaz reported a depth of 11,034 m in 1957 at a spot it called what?
Mariana Hollow
The figure has not been confirmed by later surveys.
Q 13The Challenger Deep lies within the exclusive economic zone of which country?
Federated States of Micronesia
The US Mariana Trench Marine National Monument, created in 2009, covers only the parts inside American waters.
Q 21In 1963 Trieste was used to search for which lost nuclear submarine?
USS Thresher
It found wreckage 2,560 metres down off New England and earned a Navy Unit Commendation.
Q 22Which Japanese remotely operated vehicle reached the deepest part of the trench in 1995?
Kaikō
It set a diving record of 10,911 metres and collected mud samples in 1996 that turned out to contain living organisms.
Q 23Which film director dived to the bottom of the trench in March 2012?
James Cameron
He piloted the Deepsea Challenger to 10,908 metres in the fourth-ever descent.
Q 14What is the closest land to the Challenger Deep, about 287 km to the south-west?
Fais
It is one of the outer islands of Yap; Guam lies 304 km to the north-east.
Q 15The Challenger Deep is made up of how many basins arranged from west to east?
Three
Each is 6 to 10 km long and about 2 km wide, separated by mounds 200 to 300 metres high.
Q 16Trieste, which made the first crewed descent to the bottom of the trench in 1960, was what type of vessel?
Bathyscaphe
It carried Jacques Piccard and Don Walsh, and used iron shot for ballast and petrol for buoyancy.
Q 17Who designed the vessel Trieste?
Auguste Piccard
The Swiss scientist was the father of pilot Jacques Piccard; the US Navy bought the craft in 1958 for $267,000.
Q 18How long did Trieste take to descend to the bottom in 1960?
4 hours 47 minutes
It sank at less than a metre per second, and the ascent took 3 hours 15 minutes.
Q 19What alarming event happened to Trieste as it passed 9,000 metres?
An outer window pane cracked
The Plexiglas pane shook the whole vessel, but the crew pressed on to the bottom.
Q 20The 1960 Trieste dive was the final goal of which US Navy programme?
Project Nekton
The series of dives was conducted in the Pacific near Guam.
Q 24Deepsea Challenger was built in which city?
Sydney
Engineer Ron Allum, a cave diver, invented a syntactic foam called Isofloat that made up 70% of the craft's volume.
Q 25Deepsea Challenger's syntactic foam replaced what flotation method used by Trieste?
Petrol-filled tanks
The foam is made of tiny hollow glass spheres set in epoxy resin.
Q 26Who set a record 10,928 m descent in April 2019 and first dived the Challenger Deep more than once?
Victor Vescovo
He dived four times in a week in the DSV Limiting Factor, a Triton 36000/2 submersible.
Q 27Vescovo's Five Deeps Expedition of 2018-19 set out to reach the bottom of every what?
Ocean
He had already completed the Explorers Grand Slam of both poles and the Seven Summits.
Q 28Vescovo's submersible was called Limiting Factor; what was its support ship named?
Pressure Drop
The pairing was reported to cost about US$50 million including three robotic landers.
Q 29Which former astronaut dived to the Challenger Deep with Vescovo on 7 June 2020?
Kathryn Sullivan
The former NOAA administrator descended to the Eastern Pool.
Q 30Kelly Walsh dived to the Challenger Deep in 2020, following his father, who reached the bottom in which year?
1960
Sixty years after his father, he spent four hours on the bottom of the Western Pool.