The submersible being lowered into the water, with a lady poking her head out smiling at the camera and giving a thumbs up.

The specially built submersible can only fit two people for the trip to the bottom, which takes 12 hours in total.

Image courtesy Dr Kathy Sullivan

Water from the deepest point on Earth joins the Museum collection

Last year an expedition to the Mariana Trench made history by conducting the deepest crewed dive ever completed as it descended 10,927 metres into the Challenger Deep.  

But the dive made history in a second way, as it included the first woman ever to descend into the Deep, none other than the astronaut Kathy Sullivan.

Joining this trip was Durdana Ansari OBE, the first Muslim Commander in the Royal Navy, who was invited by British-American Explorer Vanessa O’Brien.

Vanessa became the first British woman to dive to Challenger Deep and arranged for water samples taken at 10,916 metres to be collected for the Museum after being inspired by research the Museum produced showing the effects of ocean acidification overtime on single-cell organisms. 

Durdana then helped transport these water samples from one of the most extreme and least studied environments on the planet to the Museum.

During June 2020 an expedition of international crew set sail destined for the Mariana Trench in the Pacific Ocean.

The goal: to go deeper into the ocean than anyone has before. 

Durdana sits on a bench in a cafeteria smiling wide at the camera.

Durdana was invited on the trip to give her unique perspective on the expedition.

Image courtesy Dr Kathy Sullivan

Brought together by retired naval officer turned deep sea explorer Victor Vescovo, the team included deep sea specialists, but also former astronaut Kathy Sullivan and renowned mountaineer Vanessa O'Brien.

Invited along was Durdana Ansari, a former journalist who now works to improve the diversity and representation in her role as an Honorary Commander of the Royal Navy.

'It was an opportunity to show the expedition through my eyes, as the first ever Muslim Honorary Commander for the Royal Navy,' explains Durdana. 'I wanted to tell the story in my own way, whatever I saw and whatever I did.'

But the expedition was also used as a way to secure an incredibly rare sample of water for the Museum from the deepest part of the ocean. 

Going half way across the planet during a pandemic is not how it was meant to happen, but after three days of travelling, multiple tests and time spent in quarantine, Durdana made it Guam and onto the DSSV Pressure Drop, the boat that would whisk her off to the Mariana Trench.  

'Getting on the Pressure Drop was the most amazing welcome,' recounts Durdana. 'My heart had a different heartbeat, all along it changed.

'I had no idea if this kind of experience would ever happen again, so I cherished every second of it.'

The Pressure Drop boat at sunset on dark blue water.

The DSSV Pressure Drop set sail from Guam in the Pacific, and took about 24 hours to get to the trench

© Tamara Stubbs

The boat carried around 30 people out into the ocean, with the journey out taking around 24 hours. During this time the boat would roll and turn with the power of the vast ocean, the waves breaking against the boat and coming halfway up the porthole in Durdana's cabin.

'We stayed on the trench for ten days, during which the crew conducted six dives in the submersible,' explains Durdana. 'The sub can fit two people, with Victor as the diver and then another a passenger. The first dive included Kathy.

'So Kathy became the first American woman to walk in space, and then the first woman to go down to the deepest part of the ocean. It felt like such a special day.'

Each complete dive takes 12 hours. The submersible takes about four hours to go down, spends another two and a half hours going along the bottom, before spending another four hours to come back up.

Going that deep underwater is a truly astonishing feat of engineering and endurance.

A view across the Pacific Ocean with the horizon in the distance.


The Pacific Ocean is vast, but hidden beneath its waves is a world almost beyond imagination and barely explored 

© NOAA Photo Library/Flickr CC BY 2.0

A dive into the unknown

At the surface of the ocean sunlight breaks through the water, feeding blooms of tiny plankton, powering vast coral reefs and warming the top layer of water.

Most species in the oceans live within just a few hundred metres of the surface, taking advantage of these warmer waters and the energy that the sun provides.

By the time you reach just 200 metres beneath the surface, you enter the twilight zone. All light visible to the human eye has been filtered out and the inky black water has dropped to just four degrees.

So little light penetrates down to this layer that primary production, that is the production of energy using carbon dioxide dissolved in the water, becomes impossible.

It is in this dark region that species start to have to create their own light, with many fish and invertebrates becoming bioluminescent. They flash brilliant yellows, reds and blues for a variety of reasons, such as to attract prey, mates or even to confuse predators.

Going deeper still and the things start to get even more extreme. The deepest diving mammal, the Cuvier's beaked whale, taps out at around 2,964 metres, and by 4,267 metres you reach the average depth of the world's oceans.

The temperature here hovers just above freezing, while the enormous weight of water above exerts an astonishing amount of pressure. This has a dramatic influence of the species of animals that, despite all the odds, still manage to thrive at these depths. 

A bed of brown mussels on the sea floor with tiny white crabs in and amongst the mussels.

Many of the seamounts and hydrothermal vents and are covered in beds of mussels, which provide amble homes for white galatheid crabs and shrimp as seen here.

©NOAA Photo Library/Flickr CC BY 2.0

A brown and grey fish swims above a green coloured rock.

The abyssal grenadier is found in all the world's oceans, living at depths ranging from 800 to 4,000 metres.  This one was photographed off the coast of California at 2,253 metres.  

©NOAA/MBARI/Wikimedia Commona

The muddy, empty plains that stretches for thousands of kilometres in all directions at the bottom of the Pacific Ocean are home to a huge diversity of marine invertebrates that live in the sediment feeding on the bits of food that steadily fall as marine snow. Enormous towering seamounts that rise from these open seafloors support a plethora of crustaceans such as shrimps and crabs. Even some species of fish, like the abyssal grenadier, manage to live down here.

But there is still further to go.

Some parts of the seafloor are ripped open, huge tears plunging ever deeper into the Earth. One of these canyons, stretching north to south for 2,500 kilometres in the western Pacific, is the Mariana Trench.

The deepest point of the Trench is the Challenger Deep, so called as it was first measured during the Challenger expedition in 1875. Using nothing but a weighted rope, they recorded a depth of 8,184 metres, which is incidentally almost exactly the same depth that the deepest known vertebrate has been recorded after a snailfish was filmed at 8,178 metres in 2017.

These extraordinary creatures can be found in many of the deep oceanic trenches and are highly adapted to these extreme conditions. Looking not unlike giant pinkish-white tadpoles, they have large heads and small eyes, are covered in thin gelatinous skin dotted with a well-developed sensory system and even produce pressure-tolerant cartilage and pressure-stable proteins. 

A pale creamy coloured snailfish, looking like a giant tadpol with a huge head and and long thing tail, lying on a metal table.

The deepest known vertebrate is the Mariana snailfish, which has a whole suite of adaptations for living under extreme pressure. 

©Gerringer M. E. et al/Wikimedia Commons

Yet even the Challenger expedition did not reach the bottom.

It would not be until the 1950s that the generally accepted deepest depth of around 10,900 metres would be recorded, although there are a few unrepeated measurements of over 11,000 metres. At this depth the temperature inside a submersible is below freezing, while the sheer weight of water above exerts an unfathomable pressure equivalent to eight tons per square inch, or more than 1,000 times the pressure we experience at sea level.

Life, however, still thrives. 

A sample from the deep

Kathy Sullivan wearing a head set sits next to Victor Vescovo in a dark room. Both of them have huge smiles, as they sit in front of a bank of brightly coloured, glowing buttons.

Dr Kathy Sullivan (left) sits next to Victor Vescovo (right) during the expedition on board the DSSV Pressure Drop.

Image courtesy Dr Kathy Sullivan

On a day when the rest of the world was coping with the COVID-19 pandemic, Victor and Kathy descended down to 10,927 metres making history in more ways than one.

Not only is this the deepest anyone has ever gone, but Kathy became the first woman ever to go down into the Challenger Deep. In the process of this, she is now the only person ever to have walked in space and descended to the deepest point in the oceans.

Vanessa, who also accompanied Victor down into the depths, was keen to collect a sample of water from the bottom of the trench, one of which the Museum was lucky enough to receive. 

While during the dive to the bottom the crew saw little in terms of life (although they did spot some ever-present plastic), it is hoped that these water samples can reveal otherwise.

It is known that some invertebrates can survive the freezing temperatures and crushing pressure, such as some of the largest single-celled organisms. Known as Monothalamea, these giant amoebae can reach over 20 centimetres in size.

It is hoped that suspended within the water sample are microorganisms and fragments of DNA that could reveal some of the extraordinary creatures which live in the Challenger Deep.  

A view out of the window of the deep sea submersible, showing a pile of rocks lit in a blue-green light.

It took around four hours for the submersible to reach the bottom of the trench, where the temperature is only just above freezing and the pressure more than 1,070 times that at sea level.

Image courtesy Dr Kathy Sullivan

A view out of the submersible window showing a flat, muddy plain and nothing else.

While the expedition saw nothing but plastic at the bottom of the trench, life is known to survive at the bottom and it is hoped that the water sample will help reveal what lives there. 

Image courtesy Dr Kathy Sullivan

Dr Anne Jungblut is a researcher at the Museum who focuses on microorganisms that live in extreme environments.

'We know less about the bottom of the ocean than the surface of the moon,' explains Anne. 'Very few people have been to the deep sea, and so it is a really exciting place.'

The water sample doesn't look like much, to the degree that after transporting the sample back to the UK and storing it in her fridge Durdana was slightly worried she might accidentally use it to cook with. But what it represents and the secrets it could hold are invaluable.

'It looks very unsuspecting,' says Anne. 'It just looks like a drinking water bottle filled with murky water, but it is really special. It is still quite rare to have samples from down there, as it takes a lot of time, effort and logistics to get them.'

In addition to the water sample being tested for DNA to see what may be living down there, it also offers another astonishingly rare opportunity. When the Challenger expedition plunged the depths of the Trench over 100 years ago, it too collected samples of water from the deep which are still held by the Museum. This means that researchers may now be able to compare this modern sample with those collected in 1875, giving us an insight into how things may have changed.  

Four people, including Kathy Sulivan, Victor Vescovo and Durdana Ansari standing on the deck of the ship holding an English flag between them.

Durdana is a former journalist who now works to improve the diversity and representation in her role as an Honorary Commander of the Royal Navy.

Image courtesy Dr Kathy Sullivan

But the expedition has given even more to Durdana:

'That day I handed the sample over to the Museum was the finest day of my life. Bringing that water back made me feel so special. It made me cry, let's put it that way.'

Sailing over the deepest part of the Earth and witnessing these incredible dives has also had a far deeper impact.

'Going to the Mariana Trench has changed the way I think,' says Durdana. 'It has changed the way that my mind works.

'You are a little drop in a huge ocean. Yet this trip has made me connect with that entire ocean. I have taken it into my soul and it has become part of me. In front of that huge ocean, it has made me an even more humble person.'