On the morning of June 7th, the JOIDES Resolution threw off its mooring lines and set sail towards the North Sea. With the port of Amsterdam roughly 30km inland, Expedition 403 would begin with panoramic views of the Dutch countryside as it made its way towards the sea. Giant modern windmills towered over the ship as two tugboats led the way to Lock IJmuiden, which is used to control water height in the canals that lead into the densely populated city center. With Amsterdam sitting so far below sea level, the attention given to climate and rising oceans is out of necessity. The lock acting as a gate into the North Sea served as an oddly appropriate beginning for Expedition 403—the drilling destination can be considered a sort of “gate” into the Arctic, and a better understanding of it could have a direct effect on the predictions of rising sea levels.
The Fram Strait is a deep-water passage that connects the Arctic Ocean and the Northern Atlantic. Sitting between Greenland and Svalbard, the exchange of heat, moisture, and salt between the two oceans is a strong forcing mechanism for climate change both regionally and globally. A significant focus for many of the researchers onboard is the modality of decay of a former ice sheet that covered Svalbard and the Barents Sea roughly 21.000 years ago and shared many characteristics with the presently most vulnerable ice sheet on the planet, the Western Antarctic Ice Sheet (WAIS).
The lock slowly filled with water and opened its gates, leaving the tugboats behind and revealing open waters ahead. Still far from the first sampling site, the transit up along the coast of Norway would take seven days, with waves reaching as high as four meters. After onboarding and safety trainings the scientists would take the long transit to break into working groups and prepare for the arrival of samples. As the ship made the voyage further north the sun would hang higher and longer throughout the day. On the third day of transit, the faint glow of dusk would be the closest thing to night the crew would experience over the next two months. During the summer months, at higher latitudes, the sun will just run laps around the boat, never dipping below the horizon line.
The mix of sea ice movement and small window of seismic opportunity (seismic tests are only permitted in June due to vulnerable whale migration patterns in the region) would lead the expedition to settle on the eastern slope of the Vestnesa Ridge as the first sampling site. Exactly one week from departure, the crew would arrive on site. Greeted with a sea as calm as glass, drilling preparation would begin almost immediately. After the long transit the excitement of the science party was palpable in the labs as everyone huddled around the door to the catwalk waiting for the first core on deck. Friday evening at roughly 9:00pm, the first core would begin making its way up the drill pipe. In the last moments Lucinda Duxbury, a microbiologist from the University of Tasmania, had the brilliant idea to play “Ecstasy of the Gold” by Ennio Morricone over the lab’s sound system. In an appropriate pairing, the spaghetti western’s orchestral music played as the first core arrived onto to the catwalk, successful sample retrieved.
After the first core arrived on deck, the stream of samples was continuous. Deemed a high recovery expedition, the total amount of core recovered during Expedition 403 is anticipated to be over 5,000 meters. The flow of samples remained uninterrupted until challenges arrived midweek.
The indications of gas hydrates downhole posed a potential safety risk, and although not an unexpected complication for the region, evidence was showing a higher potential presence than anticipated. With the help of the trade knowledge of the drill crew and technical support staff, who constantly monitored gas safety measurements, operations proceeded with caution, ultimately leading to over one kilometer of core successfully retrieved.
Under the guidance of the onboard ice navigators Victor Gronmyr and Paul Ruzycki, the decision was made to head northwest to our next drill site. Thrusters will be raised shortly, and to the western slope of the Vestnesa ridge the team will go.
Our ocean is an incredibly vast and mysterious place. And there is no place where that is more evident than the deepest ocean area in the world: the legendary Mariana Trench. Located east of the Philippines, the Mariana Trench lies in the Mariana Archipelago in the western portion of the North Pacific. The greater area of the Mariana Trench Marine National Monument is made up of more than 95,000 square miles of ocean. Beneath these waters lie incredibly complex aggregations of submerged islands and volcanoes … and of course, an astoundingly massive trench.
Dive in with us to have your biggest questions answered about the famed Mariana Trench.
How deep is the Mariana Trench?
The deepest part of the Mariana Trench, known as Challenger Deep, is almost 36,000 feet below the ocean’s surface. For context, Mount Everest is about 29,000 feet above sea level, so the Mariana Trench is about 7,000 feet deeper than Mount Everest is tall. For one more comparison, the RMS Titanic lies at a depth of about 12,500 feet below sea level. The Challenger Deep is in waters nearly three times deeper than this ship’s final resting place.
Due to its enormous size, the Mariana Trench has at times been affectionately nicknamed the Grand Canyon of the ocean. This is certainly a picturesque image, but don’t let the mammoth size of this U.S. national terrestrial park fool you into thinking the Mariana Trench matches its size. The trench’s footprint is estimated to be 120 times larger than the Grand Canyon’s, and to reach the bottom of Challenger Deep, you’d need to descend through almost six Grand Canyons stacked on top of each other before you’d reach the seafloor.
Oh … and did we mention it’s five times wider than it is deep? It’s about 43 miles wide!
What is Challenger Deep, and how long would it take to reach it?
Challenger Deep is the deepest point of the Mariana Trench. Fewer than 30 people have ever journeyed to this area. The trek below the surface is long, dark and time-consuming, and it’s not an expedition considered lightly by scientists and explorers.
The first people to descend into the depths of this area in 1960 were oceanographers Jacques Piccard and Don Walsh, and it took them close to five hours to reach Challenger Deep. Since then, more advanced submersibles have been created, but it still takes two to four hours for modern vessels to reach such depths. For example, explorer and filmmaker James Cameron reached the seafloor in a little more than 2.5 hours in the first documented solo submarine dive to the area, and it took oceanographer Dr. Dawn Wright about four hours in 2022. It is crucial that these submersibles descend slowly and steadily beneath the surface, as the immense water pressure compounds with every mile a submersible descends. Speaking of pressure …
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What is the water pressure at the bottom of the Mariana Trench?
If you thought the depth of the Mariana Trench was its only jaw-dropping feature, think again. Water pressure is one of the most important factors affecting deep-sea life. In the ocean, pressure increases by one atmosphere for every 33 feet (10 meters) of depth. One atmosphere (a unit of measurement for pressure equivalent to average air pressure at sea level) is equal to about 14.7 pounds per square inch (PSI), which is the approximate standard atmospheric pressure at sea level. If you were to convert atmospheric pressure into weight, one atmosphere is about the weight of a bowling ball. Stay with me, friends.
If a vessel were to dive 2,000 feet below the surface, the pressure would equal that of 60 bowling balls stacked atop every square inch of that submersible. But 60 bowling balls is simply nothing compared to the pressure in the Mariana Trench. The atmospheric pressure at the depths of Challenger Deep is equal to about 16,000 PSI. That pressure is about the same as the weight of an entire full-grown elephant on every square inch of a submersible!
Need a more extreme comparison? If a human were to be placed at the bottom of the Mariana Trench, the pressure would be equal to that of 50 jumbo jets piled on top of a person!
Do any animals live in the Mariana Trench?
The depths of the Mariana Trench come with immense pressure and extreme darkness, but somehow, life finds a way to survive. Organisms that live at an extreme depth, like that of Challenger Deep, have to be highly adapted to low temperatures (typically just above freezing), high pressure and virtually no light at all.
Species found in the depths of the Mariana Trench might look vastly different from animals from other ocean depths because their anatomy has been refined to thrive in harsh conditions. At such great depths, these animals typically depend on chemosynthesis (using nutrient-rich waters being pumped out of hydrothermal vents) or descending detritus (dead matter that has fallen from higher parts of the ocean) for food, such as whale falls. Just a handful of these animals include species of octopuses and squids, sea cucumbers, amphipods, sea jellies, shrimp, sea worms and some wild-looking fish!
In 2025, more than 7,000 new species were discovered in the Mariana Trench, including the hadal snailfish (Pseudoliparis swirei). This is the deepest-dwelling fish currently known to science. Now, the fish has been dubbed “the Mariana snailfish.”
How was the Mariana Trench formed?
The process by which the Mariana Trench was created is a geologically fascinating one known as subduction. On the Earth’s surface, there are thin plates that cover the planet’s mantle, which is made of molten rock. If two of these plates collide, one pushes down into the Earth’s mantle while the other is pushed over the bottom plate. When this happens, a trench is formed from the drag of the bottom plate. This process can sometimes create incredibly strong earthquakes. The plates that forged the Mariana Trench’s creation are estimated to be up to approximately 180 million years old.
This trench was unknown to scientists until 1875. It was then that a team of explorers on the HMS Challenger measured the depth of the sea by simply lowering a weighted rope into the water. They were baffled when they measured that first portion of the seafloor to be five miles below the surface. And so was born the origin of some of the most daring deep-sea explorations known to mankind to date.
Is the Mariana Trench protected?
The Mariana Trench is in waters off Guam and the Mariana Islands. The region is protected from some human activities under its status as a marine monument. The creation of the Mariana Trench Marine National Monument signified that international, national and local leaders all recognize the importance of protecting this area.
However, just because the region is protected does not mean it’s not vulnerable to modern threats to ocean health. Plastic bags have been spotted in the Mariana Trench during several expeditions, highlighting the far-reaching impact of the marine debris problem. No corner of our ocean is safe from the ever-present threat of plastic pollution. The reality of a changing climate makes the future well-being of wondrous places like the Mariana Trench uncertain. What’s more: More than 70% of the global ocean has yet to be mapped. And what we don’t yet know about, we cannot wisely work to protect.
It’s up to us to work together to defend our ocean, from the sandy shores of our favorite beaches to the deepest, darkest parts of the sea. Together, we can work to protect our ocean as a whole, which ultimately helps protect treasured places like Challenger Deep.
Find out how you can join Ocean Conservancy’s wave of momentum to secure a healthy ocean and a thriving planet, forever and for everyone!
The post The Mysteries of the Mariana Trench appeared first on Ocean Conservancy.
Intro
At the western tip of Luzon, which is the biggest island of the Philippines, lies the small coastal town of Bolinao. Tourists seldom find their way here as it takes around seven hours to get here by bus from Manila. Still, you can spot foreigners walking around every now and then, but they really stand out among the Filipinos. A reason for their presence is often that they study or work at the Bolinao Marine Laboratory (BML), which belongs to the University of the Philippines (UP). It is one of the seven research institutions participating in the GAME project 2026. Every year, GAME brings together Master’s students from all over the world to experience different cultures and conduct globally replicated experiments in marine ecology.
This year’s Team Philippines consists of Jona, a Filipino master student of Marine Biology at the University of the Philippines, and Konstantin, a German student who is enrolled in the Master programme „Ecology and Evolution“ at Freiburg University. As part of GAME 2026, we are currently staying at BML for 6 months to run experiments about the influence of underwater soundscapes on the colonization of marine hardbottoms.
Where are we?
At the BML, we live in a dormitory together with many other students and scientists mostly from the Philippines and a few international interns. At almost any time of the day there is someone in the kitchen to hang out with, eat together, or simply have a chat. It is easy to make friends in this little community. The way to work is just a short walk along a forest path, where we can pick mangos for a snack and spot butterflies, birds, or even wild macaques climbing through the trees. After crossing a street, we reach the institute. But instead of enjoying the cool temperatures of the laboratories, we spend most of our working days outside, doing fieldwork in or near the water.
On Fridays, Konstantin experiences real Filipino culture during an almost weekly party at the institute with karaoke and lots of food and drinks. And Jona even brought some German culture to the Philippines by baking German bread for everyone.
What do we do?
Even though Bolinao is a remote place, it can get quite loud. Tricycles and jeepneys pass by, children play basketball in the streets, and karaoke can be heard almost everywhere and at any time. But just a few meters offshore, the soundscape changes. Beneath the surface of the ocean, you enter a world filled with sounds that are not so familiar to humans. When you dive down, alongside the rhythm of your own breathing, you might hear the crackling snaps of shrimp, the grunts of fish, or the rumble of waves rolling overhead. Together, these sounds form a natural underwater symphony which, however, can easily be interrupted by the noise of passing boats.