The edge of the briny pool, the first to actually have a thriving ecosystem around it. Ocean Exploration Trust

A so-called “Jacuzzi of Despair” has been found at the bottom of the Gulf of Mexico, not far offshore from New Orleans. Despite being rather innocuous in appearance, this super-salty brine pool – about 30.5 meters (100 feet) in circumference and 3.7 meters (12 feet) deep – rapidly squeezes the life out of anything unfortunate enough to wander in, from crabs to fish. The sea is dark and full of horrors, it seems.

This oxygen-depleted “deadpool” was found by an Ocean Exploration Trust expedition of research scientists using a remote-controlled submersible called Hercules back in 2014. Erik Cordes, an associate professor of biology at Temple University, returned a year later with a three-person sub to get a closer look, and described their findings in the journal Oceanography.

“It was one of the most amazing things in the deep sea,” Cordes told Discovery News. “You go down into the bottom of the ocean and you are looking at a lake or a river flowing. It feels like you are not on this world.”

The deadpool at the bottom of the sea. EVNautilus via YouTube

The briny death zone is five times saltier than the surrounding seawater, and any new inflowing, dense, briny water topples over the rocky seafloor and into it, like a small underwater waterfall. This salty pool, which also has highly toxic concentrations of methane and hydrogen sulfide, cannot mix with the surrounding sea and so keeps accumulating more brine over time.

During the Jurassic period, between 200 and 145.5 million years ago, a shallow sea existed on the site of the current Gulf of Mexico. As plate tectonics continued its inexorable march onwards, this sea was eventually severed from the rest of the ocean. In an incredibly warm world, this isolated sea began to evaporate, which ultimately left behind a mass of salt.

Eventually, the evaporated inland sea was flooded as it was once again connected to the world’s oceans, but by this point, vast layers of salt several kilometers thick had already been covered by insoluble sediment. Remarkably, as the weight of seawater squashed this salt down, some of it was forced back up onto the seafloor via a process called “salt tectonics.”

This salt then interacted with the seawater, dissolved, and formed clouds of brine that settled on the seafloor. This is where this particular deadpool came from, and it certainly has several companions that have yet to be discovered. They all exist beneath the halocline, a visible boundary with the dense brine clouds beneath it and regular seawater above.

It is possible for some specialized organisms, including a few mussels, to live in the briny pool. Ocean Exploration Trust

Although bacterial life can handle the extremely inhospitable conditions, larger creatures cannot, with some exceptions. Giant mussels with gills impregnated with symbiotic bacteria are able to survive by feeding off the noxious gases there, alongside some tube worms and shrimp.

The reason these creatures may be drawn to the hostile killer puddle is due to its unusual warmth: it’s a toasty 18.3°C (65°F) there, which is far more appealing than the frigid surrounding sea. Any creature that cannot handle the harsh conditions gets pickled and preserved in the salt as they perish.

Although extremophiles or otherwise resilient organisms have been found in some hostile places before – including in deep sea hydrothermal vents, and even inside the Earth’s crust – this is the very first time they have been seen around a brine pool. Some of the creatures could resemble life we may find deep in the oceans of worlds beyond our own.