The Underwater Lakes That Shouldn't Exist And the Strange Secret They Hide

A mile beneath the Red Sea, scientists found something that looked…impossible. At a depth of exactly 1,770 meters, cameras aboard the RV Ocean Explorer revealed a sharp, dark boundary stretching across the seafloor of the Gulf of Aqaba. It looked like a lake, and in a sense, that's exactly what it was. The discovery was made during the 2020 NEOM OceanX Red Sea Expedition, involving researchers from OceanX, the University of Miami's Rosensteil School, King Abdullah University of Science and Technology, or KAUST, and other international institutions. What they eventually mapped wasn't one isolated patch of strange water. It was an entire complex. One main brine pool covered approximately 10,000 square meters, accompanied by three smaller pools. And inside the largest one, researchers discovered sediments preserving at least 1,200 years of environmental history. But that wasn't the strangest part. The water was hypersaline, oxygen-starved, and chemically hostile to most animals. Yet around its edges, scientists found microbial communities adapted to conditions that appear almost alien. This is DiscoverTube, and today we're descending into one of Earth's most extreme environments, and into a discovery that could help scientists understand how life survives where it seemingly shouldn't. The 1,770-meter discovery. The discovery was led scientifically by a team including marine geoscientist Sam J. Perkis of the University of Miami Rosensteil School of Marine, Atmospheric, and Earth Science, alongside researchers including Hannah Czerniski, Peter Swart, Arash Sharifi, Amanda Ollert, Fabio Marchese, Francesca Benzoni, and others. Their findings were published in Communications, Earth, and Environment. Part of Nature Portfolio in June 2022. But the discovery itself happened two years earlier. During its 2020 Red Sea expedition, the 87-meter research vessel Ocean Explorer spent weeks investigating the seafloor off Saudi Arabia. And the scale of that mission was enormous. According to OceanX, the expedition accumulated approximately 960 hours and 3,696 kilometers of Ocean Explorer operations. Researchers mapped approximately 4,307 square kilometers of seabed in high-resolution 3D ROVs, and submersibles accumulated another 831 hours of operations. Five potentially new species were identified during the wider expedition. Twenty species had their known geographic or depth ranges expanded. Three ancient shipwrecks were discovered. And then, there was the brine pool. At 1,770 meters beneath the surface, researchers encountered something never previously documented in the Gulf of Aqaba. The Neom brine pools. The researchers named the newly discovered system the Neom brine pools. The largest pool measures approximately 10,000 square meters. Three much smaller pools, each covering less than approximately 10 square meters, lie nearby. But location makes this discovery particularly unusual. Previously known deep Red Sea brine pools were generally associated with the central rift system or continental shelf. The Neom pools were different. They're located in the Gulf of Aqaba and only about two kilometers from the Saudi Arabian coastline. For comparison, the previously known Thu'al seeps lie roughly 25 kilometers offshore. That difference of more than an order of magnitude turned the Neom pool into something more than an unusual ecosystem. It became a geological recorder. The 1,200-year archive. Because the pool is so close to land, material produced by coastal events can reach it. Flash floods can carry sediment offshore. Earthquakes can destabilize underwater slopes. Tsunamis can transport terrestrial material into deeper water. Normally, biological activity can disturb layers deposited on the ocean floor. Animals burrow. Sediment gets mixed. The original sequence becomes harder to interpret. Inside an anoxic brine pool, that process can be dramatically reduced because larger sediment-burrowing animals cannot survive there. When Perkis and his colleagues extracted sediment cores from the Neom pool, they found preserved layers spanning at least 1,200 years. Some deposits were interpreted as turbidites, potentially associated with flash floods and seismic activity. Others contained terrestrial material consistent with tsunami-related transport. So this strange underwater lake isn't merely preserving organisms. It's preserving disasters, layer after layer, century after century. The technology that found it. Researchers didn't discover the pools simply by looking through a window. The OceanX expedition combined several sophisticated mapping systems. The RV Ocean Explorer carried hull-mounted Kongsberg EM712 and EM304 multibeam sonar systems. These instruments operated across frequencies of approximately 70 to 100 kHz and were configured to provide a minimum across-track resolution of about 10 meters. Researchers also collected CTD profiles measuring conductivity, temperature, and depth. An Acoustic Doppler Current Profiler, or ADCP, measured water movement. But once the pools were located, scientists needed to get much closer. That's where the Argus Mariner XL remotely operated vehicle became critical. The ROV is rated for operations down to approximately 6,000 meters. It allowed scientists to record high-resolution imagery, collect sediment cores, and directly sample the unusual brine. Suddenly, something first visible as an anomaly on the seafloor could be physically analyzed. And the chemistry confirmed what the cameras suggested. This was water unlike the ocean immediately above it. The Density Barrier Average ocean water contains roughly 35 grams of dissolved salts per kilogram of seawater. Although values vary significantly between regions, the Red Sea itself is already unusually saline compared with much of the global ocean. But deep-sea brines can become dramatically more concentrated. That matters because adding dissolved salt increases water density. And density is the key to understanding why an underwater lake can exist at all. The concentrated brine becomes heavier than the seawater above it. Gravity pulls it into depressions. Instead of floating upward, it remains trapped against the seafloor. The result is a clearly visible interface. Normal seawater above, hypersaline brine below. But even this doesn't completely explain why the boundary can remain so sharp. For that, scientists have to examine how heat and salt move through water. The Double Diffusion Effect One important process is known as double diffusive convection. Imagine two bodies of water meeting. The lower layer is warmer and much saltier. The upper layer is cooler and less saline. Both temperature and salt concentration influence density. But heat and salt don't diffuse through seawater at equal rates. Molecular heat diffusion occurs roughly two orders of magnitude faster than salt diffusion. That difference can generate unusual layered circulation. Warmth escapes relatively quickly. Salt moves much more slowly. Under the right conditions, this creates persistent density stratification and helps maintain a sharp chemical boundary. But even then, brine pools gradually lose dissolved material into surrounding seawater. So why don't they simply disappear? Because beneath them is another system. One that's been operating for millions of years. The Ancient Salt Engine The Red Sea, Mediterranean and Gulf of Mexico share an important geological characteristic. All contain enormous deposits of evaporites, rocks dominated by minerals such as halite and gypsum that formed when ancient seawater evaporated. The Gulf of Mexico provides one of the most spectacular examples. During the Jurassic Period, more than 150 million years ago, restricted marine basins underwent intense evaporation. Massive salt deposits accumulated. Sediment eventually buried them. And once salt is buried beneath kilometers of younger material, it behaves differently from ordinary brittle rock. Under geological pressure and over enormous periods of time, salt can deform and flow. This process drives salt tectonics. The Salt Beneath the Seafloor Salt is relatively buoyant compared with many surrounding sedimentary rocks. When deeply buried, it can migrate upward. It forms domes, walls, ridges and enormous vertical structures known as diapirs. Some salt structures in sedimentary basins extend for kilometers. Fractures surrounding these formations create pathways for fluids. Seawater entering those systems can interact with buried evaporites. Salt dissolves. The water becomes increasingly concentrated. Geothermal heat can warm it. And eventually, pressure and buoyancy relationships can move those fluids toward the seafloor. Once concentrated brine emerges, its density takes over. It flows downhill, collects in depressions, and creates a lake inside an ocean. Sometimes, it creates something even stranger. The NOAA Brine Waterfall In 2018, the U.S. National Oceanic and Atmospheric Administration, or NOAA, sent the remotely operated vehicle Deep Discoverer into the Gulf of Mexico from NOAA ship Okeanos Explorer. The expedition lasted 23 days. During one dive into the Hidalgo Basin, Deep Discoverer crossed a low seafloor rise. Its cameras revealed a small brine pool measuring only around 1.2 meters across. Researchers observed bacterial mats, living mussels, dead mussels, exposed rock. But then the camera moved uphill. Against the tan-colored seafloor were long, dark blue-gray-black streaks. They appeared to trace dense brine flowing down the slope toward the pool. NOAA's scientists had encountered an underwater brine waterfall, and the scale of the expedition around that discovery was significant. The Gulf of Mexico mission generated more than 11.2 terabytes of scientific data. Its science team included 85 scientists, managers, and students from 35 institutions across multiple countries. And during only two ROV dives, researchers documented two previously unknown chemosynthetic communities. This is why deep sea exploration can change our picture of Earth so quickly. We haven't seen everything that's down there, not even close. The water that kills. The chemistry inside some brine pools is extreme. First comes salinity. Animals adapted to normal seawater can experience catastrophic osmotic stress when exposed to concentrated brine. But that's only one problem. Many deep brines are anoxic, meaning they contain essentially no usable dissolved oxygen. Others contain high concentrations of chemicals, such as methane or hydrogen sulfide. For ordinary marine animals, crossing the interface can become fatal. Researchers have documented fish and other animals entering hypersaline pools, becoming disoriented or convulsing, and sometimes failing to escape. Dead organisms can accumulate around the boundary. Some remains persist unusually well because the oxygen-starved environment suppresses many of the organisms and processes responsible for normal decomposition. It looks like a biological dead zone, but move toward the interface and the story changes completely. The microbial shoreline. The NEOM pool isn't biologically uniform. Scientists have identified visually distinct microbial zones around its margins. During another OceanX research mission in 2022, researchers returned to the Gulf of Aqaba to investigate these communities. Using the Argus Mariner XLROV, scientists collected roughly 500 grams of sediment from each of several microbial zones. Researchers described areas including a gray zone, an orange zone, and sediment from within the pool itself. Back aboard Ocean Explorer, the samples were preserved for molecular analysis. DNA and RNA were extracted. Then scientists went considerably deeper. They sequenced the genetic material. The DNA beneath the ocean. Researchers used an Illumina NovaSeq 6000 sequencing platform to investigate genetic material associated with the microbial ecosystem. Sequencing produced paired end reads approximately 150 base pairs long. Scientists then used metagenomic and metatranscriptomic methods to determine not only which organisms were present, but which biological processes were active. And this matters because extreme environments aren't simply filled with dormant microbes waiting to die. They're functioning ecosystems. Microorganisms process carbon. They transform sulfur compounds. Some interact with methane. Viruses infect microbial cells and influence population dynamics. An entire microscopic ecological network exists where almost no familiar animal could survive. And that brings us to one of the most important discoveries in modern biology. Life doesn't require sunlight. The ecosystem without the sun. For centuries, almost every ecosystem humans understood appeared to begin with sunlight. Plants capture solar energy through photosynthesis. Animals eat plants. Predators eat those animals. Even deep ocean communities often depend indirectly on organic material produced near the surface. Scientists call some of that falling material marine snow. But in 1977, researchers exploring the Galapagos Rift discovered something extraordinary. Hydrothermal vent ecosystems. Entire biological communities were thriving thousands of meters below the surface, beyond the reach of sunlight. The discovery demonstrated that chemical reactions could form the energetic foundation of an ecosystem. The process is called chemosynthesis. And deep sea brine environments provide another spectacular example of just how far that principle can go. If you're enjoying this scientific journey beneath Earth's oceans, subscribe to DiscoverTube. We follow the real expeditions, measurements, and discoveries revealing how much of our planet remains unexplored. The methane economy. Around methane-rich deep sea environments, microorganisms can obtain energy through chemical pathways involving methane. Other microorganisms exploit reduced sulfur compounds or hydrogen. These microbes can then support larger organisms. Mussels found around deep sea seeps provide a famous example. Some maintain symbiotic relationships with bacteria associated with their tissues. The bacteria gain access to chemical compounds. The mussels gain access to biologically useful energy and carbon. Dense communities can develop around them. Shrimp. Worms. Crustaceans. Predatory fish. The foundation isn't sunlight, it's geology. Material moves from Earth's crust. Chemical reactions provide energy. Microorganisms capture it. Animals exploit the microorganisms. Geology becomes biology. The 3.5 billion year question. And this is where brine pools become much more than a deep sea curiosity. Earth formed approximately 4.54 billion years ago. Evidence indicates that life was established at least 3.5 billion years ago. Although researchers continue debating evidence that could push biological activity even further back, that leaves one enormous unanswered question. Where did the first life emerge? In 1871, Charles Darwin privately speculated about a warm little pond where chemical compounds and energy might allow increasingly complex organic chemistry to develop. More than a century later, deep sea discoveries created another major possibility. Hydrothermal environments. Mineral surfaces. Chemical gradients. Hydrogen. Carbon dioxide. Sulfur chemistry. Natural microscopic pores inside rocks. And continuous geological energy. Could those conditions have helped transform chemistry into biology? Researchers still don't know. But brine pools have expanded the range of environments scientists must consider. Because organisms living there tolerate combinations of stresses that once seemed incompatible with life. Extreme salt. No sunlight. Very little oxygen. High pressure. Toxic compounds. And still, life. The natural time capsule. The Neome brine pools add another dimension to the story. Because the main pool's sediments preserve at least 1,200 years of geological history, Sam Perkis and his colleagues found evidence of multiple depositional events in the sediment cores. That means researchers may potentially reconstruct historical episodes of flooding, slope failure, seismic activity, and tsunami-related sediment transport. And the Gulf of Aqaba is an especially important place to obtain such records. It's part of the tectonically active Dead Sea Transform System. The region has experienced damaging earthquakes throughout recorded history. So beneath almost two kilometers of seawater sits something remarkably useful. A natural geological archive. The lack of oxygen helps protect its layers. The pool's position near the coast allows terrestrial events to leave signatures. And the sediment accumulates one event on top of another. It's almost like Earth's own seismic hard drive. The search beyond Earth. But there's another reason scientists care about environments that function without sunlight. Europa and Enceladus. Europa orbits Jupiter. Enceladus orbits Saturn. Both are icy moons. And both are believed to contain enormous reservoirs of liquid water beneath their frozen surfaces. Europa's global ocean may contain more water than all of Earth's oceans combined. Enceladus has become equally fascinating because its south polar region ejects plumes containing water vapor, salts, and organic compounds into space. The crucial point is that sunlight doesn't penetrate those oceans. For much of scientific history, that would have made them seem far less promising for life. Deep sea ecosystems on Earth change that assumption. Because sunlight isn't the only available energy source. Rock-water interactions can produce chemical disequilibria. Hydrothermal activity could potentially provide energy. And microorganisms, at least on Earth, have demonstrated an extraordinary ability to exploit those gradients. The Europa Clipper Test. NASA launched Europa Clipper in October 2024 to investigate whether Europa contains environments suitable for life. The spacecraft isn't designed to land or drill through the ice. Instead, it will perform dozens of close flybys of Europa while studying the moon with a suite of scientific instruments. Radar will investigate the ice. Spectrometers will examine composition. Cameras will map geology. Magnetic measurements will help scientists investigate the ocean beneath the surface. The objective isn't to prove that Europa contains organisms. It's to determine whether the ingredients and conditions required for habitability exist. And every strange ecosystem discovered on Earth gives scientists another model for what habitable might actually mean. The 4,307-square-kilometer lesson. Think again about what happened during the 2020 OceanX mission. Researchers mapped 4,307 square kilometers of seabed. They conducted 831 hours of ROV and submersible operations. They documented range expansions for 20 species. They reported five potential new species. They discovered three ancient shipwrecks. And they found a completely new brine pool system at 1,770 meters depth. All during one expedition. That's the bigger story. Our oceans cover approximately 71% of Earth's surface. Yet enormous areas of the deep seafloor remain incompletely explored at high resolution. Every new expedition can reveal structures, organisms, and chemical systems we didn't know existed. The neon brine pools demonstrate what can happen when advanced sonar, deep-diving robots, geochemistry, sedimentology, and genetic sequencing are brought together. First, sonar finds an anomaly. Then an ROV reaches it. Cameras reveal the boundary. Samples confirm the chemistry. Sediment cores reveal centuries of geological history. DNA sequencing reveals an active microbial world. One discovery opens five new questions. The bigger discovery. And that's why these underwater lakes matter. They're not simply strange pools of salty water. They're geological systems, chemical laboratories, biological extremes, and natural archives of Earth's past. At 1,770 meters beneath the Gulf of Aqaba, a 10,000 square meter pool is preserving a record stretching back at least 1,200 years. Nearby microorganisms survive conditions that exclude most familiar animals. Thousands of kilometers away, NOAA has documented brine flowing down the Gulf of Mexico seafloor like a waterfall. And beyond Earth, NASA is investigating an icy moon whose hidden ocean could potentially contain chemical environments unlike anything humans have directly explored. The connection is remarkable. Ancient salt changes the geology. Geology changes the chemistry. Chemistry creates an energy source. Microorganisms exploit that energy. And suddenly a place that looks completely dead becomes an ecosystem. For DiscoverTube, that's the real mystery. Scientists have already discovered life in darkness. Life without photosynthesis. Life under enormous pressure. Life beside water toxic enough to kill other animals. So perhaps the biggest question isn't whether life can survive extreme environments anymore. It's this. How extreme can an environment become before life finally reaches its limit? And if Earth hasn't shown us that limit yet, what might be waiting in the oceans we haven't explored? Tell us what you think in the comments. Could environments like the NEOM brine pools preserve clues to how Earth's earliest organisms survived? And could similar chemistry exist beneath the ice of Europa or Enceladus? Subscribe to DiscoverTube for more real discoveries, scientific expeditions, and geological mysteries hidden beneath the surface of our planet.