At some seven miles below the surface, Challenger Deep is not only the deepest part of the ocean, it's an alien world unlike no other.
This pitch black place is named for Hades, god of the underworld.Victor Vescovo/X
During the "Space Age" of the 1960s most of the world directed their gaze toward the heavens. But a select few were looking elsewhere — at the deepest part of the ocean, Challenger Deep.
On January 23, 1960, Swiss oceanographer Jacques Piccard and U.S. Navy Lieutenant Don Walsh visited Challenger Deep for the first time. Navigating from within a cramped, pressurized sphere, the two men sat huddled together, barely moving for nearly five hours as they made their descent to the Mariana Trench, some 200 miles southeast of Guam.
The watery world outside of their porthole was illuminated by a powerful beam, which soon became the only source of light as sunbeams and color evaporated during their slow descent. The eerie silence was penetrated only by conversation and, as Piccard later recalled, "crackling sounds, like ants in an ant hill, little cracking sounds coming from everywhere."
When they finally reached their goal, the two men held their breath and attempted to contact their team back at base using a specially-constructed communication device. They were unsure they would even succeed because no communication of this type had ever been attempted before.
To their relief, a voice from the other end of the line replied: "I hear you weakly but clearly. Please repeat the depth." Walsh triumphantly responded, "Six three zero zero fathoms," or some seven miles below the surface of the sea. They had touched down on the deepest part of the ocean.
This is the story of Challenger Deep, the deepest part of the ocean.
Challenger Deep, The Deepest Part Of The Ocean
Kmusser/Wikimedia CommonsMariana Trench is located between Guam and the Mariana Islands. Challenger Deep is its deepest part.
Challenger Deep is located at the southern end of the Mariana Trench, a 1,580 mile trench in the Pacific Ocean. It is the deepest ocean trench in the world, and Challenger Deep — at a breathtaking 35,462 feet deep — is its deepest part. In other words, Challenger Deep is even deeper than the 29,026-foot-Mount Everest is tall.
The ocean is divided into zones based on depths, starting with the epipelagic zone, or the sunlight zone. Challenger Deep is located at the deepest possible zone, the hadalpelagic zone, or the hadal zone, which is named after Hades, the Greek god of the Underworld.
Here, there is no light. It's cold, just above freezing, and the pressure is more than 1,000 times that of the standard atmospheric pressure at sea level. But though Hades oversaw a kingdom of the dead, scientists have found evidence of life in the deepest parts of the ocean. Scientific expeditions to Challenger Deep and the larger Mariana Trench have documented tiny creatures like plankton as well as sea cucumbers and sea fleas.
Census of Marine LifeScientists have documented sea cucumbers in Challenger Deep. This one, however, is from an expedition in the northern Gulf of Mexico.
Researchers are still learning about Challenger Deep to this day. But exploration of the area began more than 100 years ago.
The Discovery Of Challenger Deep By The HMS Challenger
Wikimedia CommonsThe crew of the 1872 Challenger expedition, which was the first to explore the depths of the world's oceans and discover Challenger Deep, the deepest part of the ocean.
Although humans have been navigating the seas for thousands of years, "the reality is we know more about Mars than we know about the oceans," marine biologist Sylvia Earle explained to Time Magazine in 2001. In fact, it was relatively recently that humans began to concern themselves with the depths of the ocean rather than just its surfaces.
Between 1872 and 1875, the Challenger Expedition set out to learn more about the ocean. According to the National Science website Dive and Discover, a British warship called the HMS Challenger was converted into a scientific vessel and set out at the end of 1872 to learn more about "ocean temperatures, seawater chemistry, currents, marine life, and the geology of the seafloor."
Led by British naturalist John Murray and Scottish naturalist Charles Wyville Thompson, the Challenger Expedition had samplers to gather mud and rock, nets to capture animals at different depths, and, importantly, sounding lines which they could use to measure the depth of the water.
National Science FoundationSounding tools used by the Challenger Expedition to measure the depths of the ocean.
By the time the crew returned to England in 1876, they'd discovered some 4,700 new species of animals and plants — and had determined the deepest part of the ocean. During their voyage around the world, they used sounding tools to discover the Mariana Trench and Challenger Deep.
In 1951, 75 years later, the HMS Challenger II returned to the same location. Thrillingly, they were able to confirm that the previous expedition had, in fact, located the deepest part of the ocean. Thus, Challenger Deep was named in honor of the original 19th-century expedition.
[I]t was not more than 50 miles from the spot where the nineteenth-century Challenger found her deepest depth," the missions's chief scientist, Thomas Gaskell, later explained. "[A]nd it may be thought fitting that a ship with the name Challenger should put the seal on the work of that great pioneering expedition of oceanography."
Less than a decade later, human beings would attempt to explore Challenger Deep for the first time.
The First Mission Into Challenger Deep
It was one thing to measure Challenger Deep from the ocean's surface. It was quite another to descend more than 30,000 feet to the deepest part of the ocean. But that's what Swiss oceanographer Jacques Piccard and U.S. Navy Lieutenant Don Walsh resolved to do.
In a U.S Navy mission cloaked in secrecy — in case it failed — the two set out on Jan. 23, 1960, to explore Challenger Deep. They climbed into a 60-foot-long Navy submersible called the Trieste, which Piccard and his father had designed for deep sea exploration, and began to descend.
Wikimedia CommonsThe Trieste, the vessel that Piccard and Walsh took to Challenger Deep.
"The buffeting waves, by covering the Trieste, have sent it into a region of eternal calm, an immense mysterious domain where the fish of the deeps open their avid eyes in the darkness, and where chilly waters are found only a few thousand feet from the eternally warm seas of the tropics," Piccard later recalled, according to a 1960 issue of National Geographic.
The descent took five, nerve-wracking hours. Piccard later wrote that the Trieste moved at the speed "of an elderly elevator" and that they soon started observing phosphorescent plankton in the dark depths. Before long, they began to surpass depths that they had explored in previous weeks.
Walsh murmured: "We are at a depth where no one has yet been."
Wikimedia CommonsWalsh and Piccard in their claustrophobic vessel.
And they still had some 10,000 feet to go.
As the two explorers neared the deepest part of the ocean, they heard a cracking sound and felt the vessel rock. Nothing else seemed to be the matter — they later determined it was the cracking of a plastic window covering, which posed no immediate danger — so Walsh and Piccard continued their descent.
Then, at 1:06 p.m. they reached Challenger Deep.
"[We had] made a perfect landing on a carpet of uniform ivory color, that the sea had laid down during the course of thousands of years," Piccard recalled.
He and Walsh stayed on the seafloor for about 20 minutes to make scientific observations. Then, they started back toward the surface. After a few hours, the sea turned from black to gray to blue. Finally, Piccard and Walsh emerged from the water — the first people to ever visit the deepest part of the ocean.
"[W]e saluted gladly; not for posterity, to be sure, not for the photographers, but for the rediscovered sun and pure air, even for the wind and the waves that submerged us each instant," Piccard wrote. "We had only one thought: profound gratitude for the success achieved, gratitude toward all those who had contributed to the success of this uncommon day."
Humans would not reach the floor of Challenger Deep again for over five decades. Although two unmanned submarines were sent on separate expeditions in 1995 and 2009 (one Japanese and one American), it was not until director James Cameron of Titanic fame plunged the depths in his own expedition that a manned vehicle would reach the bottom.
How Explorers Have Studied Challenger Deep
On March 26, 2012, James Cameron climbed into a submersible that he had co-designed and prepared to drop into Challenger Deep. In doing so, he became just the third person in history to reach the deepest part of the ocean, and the first person to an embark on a solo expedition.
"I've always dreamed of diving to the deepest place in the oceans," Cameron said according to National Geographic. "This quest was not driven by the need to set records, but by the same force that drives all science and exploration... curiosity."
Mark Thiessen/National Geographic CreativeJames Cameron's Deepsea Challenger touches down at Challenger Deep, the deepest part of the ocean, in 2012.
Unlike his predecessors, it only took the director about two and a half hours to descend the nearly seven miles to Challenger Deep. Also in contrast to the previous manned expedition to Challenger Deep, Cameron's vessel was equipped with arms to take samples from the ocean floor, as well as 3-D video cameras, which Cameron used to shoot footage for his 2014 documentary Deepsea Challenge.
But like Walsh and Piccard, Cameron experienced some harrowing moments during the descent. Because of the intense water pressure, several parts of his submersible started to malfunction.
"A couple of my batteries are dangerously low, my compass is glitching, and the sonar has died completely," Cameron wrote for National Geographic. "Plus, I've lost two of the three starboard thrusters, so the sub is sluggish and hard to control."
But despite these challenges, Cameron was able to spend three hours in Challenger Deep. He captured photos and videos, and even documented 68 new species (most of which were bacteria) before returning to the surface.
Since then, a number of other people have also been able to make the dive to the deepest part of the ocean. In 2019, investor and explorer Victor Veseco — who has also climbed Mount Everest — descended to Challenger Deep in the submersible he'd commissioned, Limiting Factor. This submersible was also used in more than a number of subsequent missions.
Richard Varcoe on behalf of Caladan Oceanic LLCVesco's Limiting Factor has been used for a number of dives to Challenger Deep.
Thus, the group of people who have visited Challenger Deep have grown. To date, more than two dozen explorers have descended into the depths of the ocean. They've documented the strange, alien-like landscape, and, sadly, bits of trash which have floated down.
There's undoubtedly still more to learn about Challenger Deep, the deepest part of the ocean. Perhaps one day it will be more accessible for regular people and not just explores. Until then, satiate your curiosity by looking through the collection of photos in the gallery above.
After this look at Challenger Deep, the deepest part of the ocean, check out some of the strangest deep sea creatures ever found. Then, read about the prehistoric fish known as the Coelacanth, which scientists thought had gone extinct millions of years ago.
