By Albert Firus and Laurenz van Bonn (GEOMAR)
As the SONNE leaves the first measurement station around the equator behind and continues further into the Bay of Bengal, technicians, scientists, and crew on board are quite busy. While for some this is almost routine, such as our technician Mario, who is on his 36th cruise already, others are gaining their first experiences on board of a research vessel these days. This includes the two students Albert (26, Geosciences) and Laurenz (21, Environmental Sciences). Albert is investigating near-surface trace metals for GEOMAR in the marine biogeochemistry working group, and Laurenz, also on board for GEOMAR, is working the chemical oceanography working group on trace gaces in the water column, particularly the greenhouse gases N2O and CH4. The two have already spent the first two weeks on board of the SONNE and describe the different impressions of their first major research cruise:
Albert: “When out of the blue on a regular workday I was asked if I´d like to join the next expedition to the Indian Ocean, my jaw dropped. Ever since the beginning of my study, it had been a constant thought and dream to be part of research expedition. When I started working for GEOMAR, it seemed like this long-held dream was finally within reach, but it would take another year until it finally happened. I immediately thought ´yes!´ and so the preparations began for our departure in April 2024.
Due to various delays, the 39 scientists had time to get to know each other in Colombo. Already, the participants seemed very motivated and helpful. This impression solidified after the SONNE set sail south-eastward, crossing the equator.
In the first few days, I was getting used to the constantly swaying ship. It´s much larger than I expected. More than once, I got lost, but luckily the ship’s crew are helpful and ready to assist. The path that everyone probably memorizes first is the way to the mess. But that´s necessary because meal times are scheduled. The dishes are delicious, varied, and energizing for the frequent physical work. This work awaits us when we reach the next station. Sometimes we reach it a night, which means night shifts are in order. When there is no night shift, our cabins are cosy, and the sleep is restful. By now, the ship rocks me to sleep.
If the dizziness ever gets overwhelming, you find a nice spot by the window or, better yet, by the railing and gaze out intothe vastness of the ocean. The blue of the water is breath-takingly beautiful. The sunsets are causing my phone´s storage to dwindle. For those who want to see mover lively sights, after dark, you can try to catch a glimpse of pink and orange squids, flying fish, or jellyfish. When the day of the week become blurred due to night shifts and no weekends, you often forget which day of the week it is. The meal plan, fish on Fridays and the ice cream on Thursdays and Sundays remind you what day it is.
“So far, I only knew research vessels like the SONNE from lectures in university. I always thought how great it would be to be part of a cruise myself, and when I got the opportunity to join SO305, my excitement was immense. When we took the first step onto the ship in Colombo, it was a great moment, but also very exciting – after all, you don´t know what to expect in the next 6 weeks. All worries disappeared faster than they came, and that is mainly due to the amazing people involved in this cruise, the great colleagues, and the crew, who are all incredibly helpful and work together superbly. The first days were filled with new impressions, I have already learned a lot, not only scientifically, but also about the importance of organization and communication on board, about being able to find collaborative solutions to every problem. I am very much looking forward to learning even more in the coming weeks and delving deeper into the world of marine science. Whenever the workload and little sleep demand a small break, I sit down on the top deck, letting my gaze wander over the incredibly blue water during the day or to the starry sky, where at clear nights you can even see the milky way. It is a very special feeling to stand on deck and see nothing but water all around, only being able to imagine what is happening in the more than 4000 meters of water below us. Being involved in the exploration of this wonder is a great feeling, and I hope this is just the beginning, and that I will eventually go on a similar number of cruises as Mario has over time. The only wish I have for the rest of the journey is that a few whales pay us a visit – they´ve been pretty elusive so far.”
Ocean Acidification
Dr Heidarzadeh’s TV interview with SkyNews on the massive M7.7 Panama earthquake on 9 October 2026
Dr Heidarzadeh’s TV interview with SkyNews on the massive M7.7 Panama earthquake on 9 October 2026. Click here for the full story.
Dr Heidarzadeh’s TV interview with SkyNews on the massive M7.7 Panama earthquake on 9 October 2026
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!
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