Buzz
Maps exist for nearly every corner of our Solar System—the Moon, Mars, and even Uranus. Yet, one place right here on Earth remains scarcely charted: the ocean floor. Although it's only a few miles beneath us, we’ve only mapped around five percent of the seafloor, making it a far greater mystery than Pluto.
The Mariana Trench, the ocean’s deepest point, stands out among the rest of the ocean floor, though we still know very little about it. With a depth of almost seven miles (11 km) and water pressure more than 1,000 times that at sea level, attempting to visit and map the trench would be nearly suicidal.
Thanks to new technology and a handful of courageous individuals willing to risk their lives exploring the trench, we now know a few things about its hidden depths. So, if you’re ever in search of a thrilling vacation destination, here’s what you might come across when visiting the Mariana Trench:
10. Dangerously Hot Water
As you descend into the depths of the Mariana Trench, prepare for an abrupt drop in temperature. At these extreme depths, the water is just above freezing, ranging from a bone-chilling 1 °C (34 °F) to a slightly warmer 4 °C (39 °F). So, it’s best to bring clothes for both freezing and slightly warmer conditions.
If you get close to the hydrothermal vents around a mile (1.6 kilometers) below the surface, make sure you’ve got your summer attire. In a world where the water is nearly ice-cold, there are several vents that release water heated to nearly 450 °C (700 °F). These vents, known as “black smokers,” spew out rich minerals that sustain the life forms in the Trench. These creatures rely on these minerals and the energy the vents provide since the Sun’s rays don’t reach that deep. It’s either stick around these hot water plumes or face extinction.
Incredibly, this scalding water doesn’t boil, even though it’s far above the boiling point. The immense pressure at a mile’s depth (more than 155 times the pressure at the surface) prevents it from boiling, but the temperature remains dangerously high.
9. Gigantic Toxic Amoebas
Imagine seeing a tiny puppy, only four inches in size. Your instinct would probably be to hug it, right? Now, picture a four-inch (10 cm) amoeba—would you still want to embrace it, or would your first thought be to run for your life?
If the latter is the case, you might want to reconsider visiting the Mariana Trench, as massive amoebas are everywhere down there. Known as xenophyophores, these single-celled creatures have likely grown so large due to the extreme conditions of their environment—cold temperatures, immense pressure, and no sunlight all contribute to their nightmarish size.
To make matters worse, these xenophyophores seem nearly indestructible, immune to many chemicals and elements that would be lethal to most species, including humans. By absorbing minerals and particles from the surrounding water, they’ve developed a resistance to dangerous substances like uranium, mercury, and lead—things that would be fatal to us in even small doses.
And don't think you'll stop encountering these cute little creatures as you descend deeper. They've been observed as deep as 6.6 miles (10.6 km), and researchers wouldn’t be shocked to find them even further down in the future.
8. Pure Liquid Carbon Dioxide
While most of the hydrothermal vents we've talked about release plain old water that could burn your skin if you're not careful, one vent takes things to a whole new extreme by expelling pure liquid carbon dioxide instead.
Aside from the Okinawa Trough near Taiwan, the Champagne Vent in the Mariana Trench is the only known underwater site where liquid carbon dioxide exists. Found in early 2005, this vent earned its name from the bubbly appearance of what scientists initially thought was harmless water, resembling Korbel champagne. However, upon closer inspection, they realized these bubbles were actually CO2.
Although ingesting pure carbon dioxide would be harmful to humans, it seems that vents like this one, called “white smokers” due to their cooler temperatures, may be the origin of life itself. As the “primordial soup” theory falls out of favor, the idea that life began in deep-sea vents, like Champagne, has gained traction. A white smoker such as Champagne, with its moderate temperatures, rich chemical composition, and abundant energy, could provide the perfect environment for life to evolve and thrive.
7. Clams
The extreme water pressure found in the Trench makes it nearly impossible for anything with a hard shell or bones to survive, which is why sea cucumbers and giant amoebas are so abundant (in case you'd already blocked those from memory). Drop a turtle down there, and its own shell would likely crush it.
The discovery of shelled creatures in the Trench, including clams, challenges the notion that nothing lives down there. These clams, found in early-2012, thrive near serpentine hydrothermal vents. The serpentine rock is filled with essential minerals like hydrogen and methane, which support the existence of life. Scientists are still uncertain how these clams have evolved such durable shells to withstand the immense pressure, and unfortunately, they aren't offering any answers.
Despite the intense water pressure, these vents release another substance—hydrogen sulfide—which is typically deadly to clams and other mollusks. Fortunately, the clams have developed a mechanism to neutralize this danger, by binding the toxic sulfide to harmless proteins, which allows them to survive in these extreme conditions.
6. James Cameron
Yes, James Cameron—the director behind one of the highest-grossing films ever made—has a deep interest in the ocean and even led his own solo expedition to the bottom of the Trench.
Since its discovery in 1875, the deepest point in the Trench, called the Challenger Deep, has only been visited by three individuals (for comparison, twelve people have walked on the Moon). The first explorers, Don Walsh and Jacques Piccard, reached the bottom on January 23, 1960. Their ship, named the Challenger, inspired them to name the area Challenger Deep, though the 'Deep' part of the name remains a mystery.
It took more than five decades before another adventurer dared to venture into the freezing, crushing depths. This time, the explorer was a filmmaker. On March 26, 2012, James Cameron descended to the bottom, capturing the first-ever images of the Challenger Deep. While more trips to the Deep are planned, none have been officially confirmed, making Cameron the latest person to reach the Earth's lowest point.
5. Ooze
What does the ground beneath the water at the beach feel like? It's most likely just wet sand. However, if you continued swimming deeper and deeper, all the way to the Trench's depths, the ground would feel radically different. This is because the entire Trench is blanketed by a thick, slimy ooze, a result of everything that has filtered down from the surface above.
Sand doesn’t really exist down in the Trench. Instead, you’ll find a layer of death. The floor is mostly composed of crushed shells and the bodies of plankton that have gradually sunk over the years. Due to the immense water pressure, everything gets reduced to a fine, grayish-yellow, almost silky sludge. Given the Trench's age (many scientists consider it the oldest part of the ocean), one can only imagine how far down this ooze stretches before the Earth itself begins.
4. Liquid Sulfur
The Daikoku Volcano lies about 40 atmospheres (414 m or 1,360 ft) beneath the surface of the Trench. While this might not sound remarkable, considering the Trench's deeper regions, Daikoku hosts one of the rarest phenomena on Earth: a lake of pure molten sulfur. The only other place in the solar system where this exists is Io, one of Jupiter’s moons. Since traveling there is a bit out of reach, you’ve probably never witnessed this spectacular sight firsthand.
Known as the Cauldron for obvious reasons, this pit of bubbling black goo burns at a scorching 187 °C (369 °F). Our understanding of it is still limited, but the white smoke rising from nearby craters hints that there could be even more sulfur in the area than in the Cauldron itself. If that's the case, this entire region might hold the answers to one of life’s greatest mysteries: the origins of life.
The Gaia Hypothesis, a controversial yet longstanding perspective, proposes that Earth functions as a unified, self-regulating system, where both living and non-living components collaborate to sustain life. Researchers are testing this theory by capturing sulfur and releasing it into the atmosphere, observing whether it survives and cycles back to land. If it does, it could lend some credibility to the Gaia Hypothesis, with sulfur potentially playing a role in Earth's ability to sustain life.
3. Nothing
Obviously, we’re not claiming there’s absolutely nothing in the Mariana Trench. That would be absurd, considering everything we've already discussed. However, no strange fish or bizarre creatures encountered on the way down will prepare you for what’s at the very bottom: absolutely nothing.
During James Cameron’s 2012 dive to the Challenger Deep, he took in as much as he could before a mechanical failure forced his return. What he found was a shocking revelation: aside from a few inch-long prawns, he was completely alone. There were no monstrous sea creatures, no extraordinary wonders of nature, no raw displays of evolutionary prowess. It was just James and his little metal capsule, drifting in a silent, aquatic ghost town with no one to converse with.
According to James Cameron, the very bottom of the ocean is 'lunar... desolate... isolated,' and during his time there, he experienced 'complete isolation from all of humanity.' Given everything we've learned about the deep ocean, it’s quite surprising to discover there isn't some ultimate, monstrous creature lurking down there. Hopefully, future expeditions to the Challenger Deep will finally reveal that Cthulhu-like terror we've all been hoping for.
2. A Monument
Sadly, no statues or underwater tourist spots have been created (yet). However, the Mariana Trench is undoubtedly a monument, and it's legally protected by the United States.
In January 2009, President George W. Bush signed a law that designated the Mariana Trench as a national monument, covering over 246,000 square kilometers (95,000 sq mi). It is the largest marine reserve on Earth, even surpassing the Papahânaumokuâkea Marine National Monument, which Bush also established in 2006.
Since the Mariana Trench is now a national monument, there are new rules for anyone hoping to visit. Within the protected area, fishing and mining are banned, so don’t pack your fishing gear. Swimming is still allowed, though, so your dream of reaching the deepest part of the ocean is still within reach.
1. Bridges
In late 2011, four rock bridges were discovered in the Mariana Trench, stretching roughly 69 kilometers (43 miles) across. These bridges seem to have formed from the meeting of the Pacific and Philippine tectonic plates. The Pacific plate slipped beneath the Philippine plate, and the seamount material from both sides collided to create the structures seen today.
One of the bridges, Dutton Ridge, was first spotted in the 1980s, though only in low-resolution images. Dutton Ridge is particularly noteworthy because of its impressive height—it's almost like a small mountain. The Ridge’s peak rises 2.5 kilometers (1.5 miles) above the Challenger Deep, although it’s still over 8 kilometers (5 miles) beneath the ocean's surface. The fact that researchers were able to discover something in the Trench, which was a mystery until recently, is truly remarkable.
Like many other mysteries of the Trench, we still don’t understand the purpose of these bridges. After all, there aren't many sea creatures that require bridges. Well, maybe the walking catfish, but they aren’t exactly known for being deep-sea explorers.
