Puerto Rico Trench: What Is Hiding At The Deepest Point Of The Atlantic Ocean?

Going down to the deepest spot in the Atlantic ocean, the Puerto Rico Trench and you won't believe what we find down there.

Ever since Jaws hit the silver screen in nineteen-seventy-five, people the world over have been terrified of creatures in the Atlantic Ocean. Since then, countless movies, TV shows, and games have tried to cash in on this deeply rooted fear.

Deep Blue Sea, Deep Rising, Underwater, Leviathan, Virus, The Abyss, and The Meg have all been based around the idea that monsters lurk in the depths. And in the popular video game Subnautica, the entire premise is based around exploring the deep ocean with futuristic diving gear, and cataloguing the strange creatures below.

It may seem like chasms deep within the ocean, containing life that looks downright alien to us, belongs purely in the realm of fiction. But these places and the bizarre creatures that live there are very much real.


We’re going to discuss the Puerto Rico Trench – the deepest area in the Atlantic Ocean. We’re gonna find out what it is, how deep it is, and the kind of strange life you might find down there.

About Puerto Rico Trench

Puerto Rico Trench, by Vsmith, Public domain, via Wikimedia Commons

Well, actually, it’s over eight-hundred times the pressure at sea level which would squash your head like a ripe melon, but don’t let that bother you.

As the name suggests, the Puerto Rico Trench is a giant oceanic trench on the boundary of the Caribbean Sea. The trench is almost 500 miles/800 kilometers long – that’s practically a fifth of the width of the continental United States.


It’s also got a maximum depth of almost 30,000 feet/8,376 metres – for context, that’s the length of about eighty-three football fields. The floor of the trench is referred to as the “Milwaukee Deep” and sometimes the “Brownson Deep.” If you descended this far below the surface of the ocean without adequate protection, you’d be crushed like a tin can.

The origin of the trench can be traced back to the Cenozoic era, and some scientists speculate that it’s been open for around seventy-million years. This means it could have shared the earth with creatures like the velociraptor and the tyrannosaurus rex.

There are a few different curiosities to be found in the Geography of the Puerto Rico Trench.

One is a complex fault system known as the Bunce Fault – after its discoverer, Dr. Elizabeth Bunce – which is not unlike the San Andreas fault in California. There was also a large underwater mud volcano discovered almost twenty-six-thousand feet deep into the trench, capable of spewing over six miles of molten mud.


Another strange and fascinating detail about the trench itself is the trench’s negative gravity anomaly, dubbed by some as the greatest of its kind anywhere in the world. NASA studies have shown that the bottom of the trench has a strong downwards pull, as though the mass beneath the trench is creating its own force of gravity.

This is partly why studying and exploring the trench has been a nightmare in the past. The gravity-disrupting power of the trench’s floor can cause most conventional navigational technology to go haywire.

This is, of course, a completely natural anomaly, and definitely not the secret base of Zeti Reticulian aliens and their fleet of anti-gravity ships.


Other than definitely not hiding secret alien bases, what else makes the Puerto Rico Trench special?

Damage caused to the “La Habanera de Infanzón y Rodríguez” building in Mayagüez due to earthquake in 1918 in Puerto Rico, by Cifuentes, Public domain, via Wikimedia Commons

Well, it all comes down to tectonic plates. According to the National Oceanic and Atmospheric Administration, in the Pacific Ocean, trenches often form in places where one plate subducts another. However, the Puerto Rico Trench, to quote the NOAA: “is located at a boundary between two plates that slide past each other with only a small component of subduction.

This is why the trench is slightly less deep than its sister trench, the Mariana trench, in the Pacific. But just because it’s smaller doesn’t mean it can’t cause huge problems for the people living nearby.

To the approximately four-million United States citizens living in Puerto Rico and The Virgin Islands, the Puerto Rico Trench is a real and present danger. It’s technically classified as an active plate boundary. If you paid attention in high-school Geography class, you’d know that this means earthquakes are a constant risk, and this area has abnormally high seismic activity, too.


Earthquakes ranging from magnitudes of 6.9 to 8.1 on the Richter Scale have been recorded as far back as 1787, each causing widespread devastation for coastal communities. However, earthquakes aren’t the only issue – tsunamis have also been a consistent and deadly threat to the region.

In 1918, an earthquake just outside of Puerto Rico caused a tsunami that drowned ninety-one. But this is actually one of the more minor incidents. After an earthquake North of Hispaniola in 1943, a tsunami struck, reaching miles inland, and drowning up to one-thousand-eight-hundred people.

Most disturbing of all, these earthquakes and tsunamis are not a thing of the past.

Victor Vescovo, by Vlvescovo, licensed under CC BY-SA 4.0 via Wikimedia Commons

Scientists and government officials estimate that the Puerto Rico Trench is and will remain an active threat to the people of Puerto Rico and The Virgin Islands. While the technology for predicting when these seismic events might occur has improved significantly, there’s no preventative measure that can be taken against these terrifying forces of nature.


In recent years, thanks to advances in submarine technology, there have been manned exploratory missions into the Puerto Rico Trench. One such expedition is that of Victor Vescovo – an incredibly wealthy American private equity investor and former naval officer – who used his vast personal resources to reinvent himself as an explorer.

In 2018, Vescovo conducted a solo-mission in a small submersible vehicle, traveling over 27,000 feet/2,100 meters down into the Puerto Rico Trench. As a modern-day adventurer, Vescovo also climbed Mount Everest, and he took great pride in traveling to both the highest point on earth, and the lowest point of the Atlantic Ocean.

So, we’ve discussed the Puerto Rico Trench, its location, its effects on the locals, and the eccentric millionaires that explore it.


How about the ecosystem of creatures that call the Puerto Rico Trench and places like it home?

The different parts of the Pelagic zone (Hadopelagic or Hadal zone – deepest), by TomCatX, Finlay McWalter, DieBuche, Public Domain via Wikimedia Commons

Oceanic Trenches are technically part of the Hadal Zone – an area between 20,000 and 26,000 feet/6,000 to 8,000 meters below the surface of the ocean. The Hadal Zone is named after Hades, the Greek name for both the God of the Underworld and the Underworld itself. As one ventures deeper into the ocean, both the variety and biomass of animals decrease.

At around 27,000 feet/8,000 feet, the Puerto Rico Trench sits perfectly in the Hadal Zone.

So, what kinds of animals – known as Hadal Fauna – could you expect to see down there?

In the deep ocean, there’s no light, and therefore, no plant life. It’s cold – reaching around 39.2 degrees (four degrees Celsius) at its highest temperatures. The creatures that exist in the Atlantic Hadal Zone need to either be extremely simple or extremely hardy. Much of this life is microscopic, such as a number of different planktons.


Of greater interest is the area just above the Hadal Zone – the Abyssal Zone. In the Abyssal Zone, we’ll find creatures that are a lot more complex than the Hadal Fauna. And in the process, we’ll realize that isn’t always a good thing.

Here are some of the strangest creatures you might find in places like the Puerto Rico Trench.

Deep-Sea Dragonfish

Deep-Sea Dragonfish, from plate 33 of Oceanic Ichthyology by G. Brown Goode and Tarleton H. Bean, published 1896, Public Domain via Wikimedia Commons

A vicious predator that earns its ominous name. The Dragonfish is found up to 50,000 feet/1,500 meters deep, with razor-sharp fangs and glowing organs (known as photophores) that compensate for the lack of light. Like the Anglerfish, the Dragonfish has a glowing barbel that hangs beneath its chin to attract prey.

And here’s an unsettling little fact about the Dragonfish: Because most of its prey are also bioluminescent, and due to the Dragonfish’s translucent skin, it could be at risk of detection from rival predators after feeding. However, our friend, the Dragonfish has a cunning mechanism to account for this issue.


The interior walls of the fish’s stomach are black, preventing its prey from shining through after consumption.

Atlantic Hagfish

Atlantic Hagfish, by Charles Keith, Public Domain via Wikimedia Commons

Another deep-sea nightmare is Myxine Glutinosa, also known as the Atlantic Hagfish, and the Slime Eel. The Atlantic Hagfish isn’t quite as terrifying as the Dragonfish, but it makes up for this by being absolutely disgusting. Half of the nickname “Slime Eel” is a misnomer, because the creature lacks a backbone and a jaw, meaning it’s not technically an eel.

The slime part, however, is upsettingly accurate.


The body of the Hagfish is covered in slime-producing glands that leaves it constantly dripping with sticky secretions. This slime is one of the most notable qualities of the Hagfish – seeing as it’s reinforced with fibers that make it durable and incredibly hard to remove. Even more concerning, Hagfish slime can expand ten thousand times beyond its original quantity, producing buckets of the noxious goo.

In an unfortunate example of the power of Hagfish slime, a truck carrying Hagfish towards South Korea – where Hagfish are a delicacy – overturned on Highway 101, in Oregon. The cargo spilled out onto the asphalt, coating the truck itself and another unfortunate car in a mountain of thick, white Hagfish slime. It’s rare that this happens anywhere above 6,000 feet/1,800 meters deep in the ocean.

Vampire Squid

Vampire squid, by Monterey Bay Aquarium Research Institute, licensed under CC BY-SA 4.0 via Wikimedia Commons

If you descend to a mere 3,500 feet/1000 meters, you might run into the Vampire Squid or Vampyroteuthis infernalis.


In spite of its terrifying name, and the fact that it looks like Cthulhu’s decapitated head, the Vampire Squid isn’t much of a threat. It’s only six inches/15 centimeters long and is believed to largely feed on small invertebrates like prawns.

The creature exists on an ocean layer pretty much entirely devoid of light, and thus, has developed full control of its bioluminescence as a defense mechanism. The squid can deploy its impressive lightshow at will to attract or mesmerize prey, but if a larger predator arrives?

The squid can turn off its lights, rendering itself completely invisible.


Gulper Eel

Gulper Eel, Public Domain via Wikimedia Commons

The legendary Gulper Eel, or Black Swallower, is present in all deep oceans across the globe. These creatures can live up to 6,000 feet/1,800 meters deep and has even more limited interactions with human scientists. However, when you find out more about the Gulper Eel and its unique eating habits, you’ll probably be grateful for that.

The creature has tiny eyes and a bioluminescent tail that allows it to navigate the darkness of the ocean depths. The light on its tail glows pink and occasionally red, and like the Dragonfish’s barbel, attracts prey.

Its size ranges from three to six feet/one to two meters – significantly larger than the Dragonfish and Hagfish – but the length of its body feels secondary to the size of its mouth. The Gulper Eel has a large mouth with a loosely-hinged jaw.


While its diet consists mainly of small crustaceans, when its favorite foods are scarce, it’s capable of unhinging its jaw and swallowing prey whole. While it’s unlikely the Gulper Eel does this often, it’s technically capable of swallowing prey the same size, or even larger, than its head. One more reason to be grateful you’re not a deep-sea fish.

Snipe Eel

Snipe Eel, from The Fisheries and Fisheries Industries of the United States, by George Brown Goode, Public Domain via Wikimedia Commons

Speaking of eels, up to six thousand feet deep in the Atlantic Ocean, you’re likely to encounter the Snipe Eel. A perfectly weird name for a perfectly weird animal. Five-feet/1.5-metres-long, and incredibly thin, the creature looks almost like a living piece of string – hence its alternate name, the Threadfish.

But that’s not the only weird nickname for the Snipe Eel. Due to its thin, birdlike face and beak-like mouth, it’s also sometimes called the Deep-Sea Duck. All things considered, this is one of the kinder traits to name this eel after, seeing as its anus is in its throat.


Unlike the Hagfish – which has no vertebrae whatsoever – the Snipe Eel actually has the most vertebrae of any creature alive on earth today, with 750 vertebrae in its long and excessively-articulated spine.


Fangtooth, by Citron, licensed under CC BY-SA 3.0 via Wikimedia Commons

Finally, perhaps residing the deepest of all, is the terrifying Fangtooth. Otherwise known as the Ogrefish, despite being only six inches/15 centimeters long, this creature really earns its monstrous names.

Dwelling up to sixteen-thousand feet/4,800 meters below the surface of the ocean, the Fangtooth can survive in locations like the Puerto Rico Trench better than any of the previous creatures – and when you see it, you’ll be immensely relieved about that.


It earned its name from its impressive set of fangs, which are actually the largest fangs in the ocean, in proportion to the size of the fish. Its terrifying teeth are too big to even fit in its own mouth – as a result, the roof of the Fangtooth’s mouth has special pockets that its larger teeth can slide into while its jaws are closed.

Good luck sleeping with that image in mind. Or with the knowledge that any of these creatures are out there, lurking in the deep. Waiting and hungry.

It’s a common cliché to say that we know more about space than we do about the deep ocean. But much like space exploration, new technologies for better understanding the depths of our oceans are being developed every year.


Places like the Puerto Rico Trench won’t always hold the mystery they do today – the real question is whether we’ll like what we find.

Featured image: View of the sea floor of the Puerto Rico Trench, by USGS, Public domain, via Wikimedia Commons