Deep-sea 'hot tub of despair’ has a nightmarish effect on all who enter it

Hot tubs are generally associated with bubbling relaxation, but there’s one pool you certainly wouldn’t want in your local spa.

The so-called “Hot Tub of Despair” is located at the bottom of the Gulf of Mexico, and its toxic waters have a horror movie-style effect on almost anything that gets too close.

The sinister bowl-shaped “tub” sits almost 1,000 metres (3,300 feet) beneath the waves and measures 30.5 metres (100 feet) wide and 3.7 metres (12 feet deep), according to Nautilus Live.

It was discovered during a 2015 field investigation into cold seeps in the region. These are places where hydrocarbons – organic compounds which make up oil and gas – escape from the seafloor and enter the surrounding section of water.

In the Gulf of Mexico, hydrocarbons are pushed out by shifting slabs of salt that formed in the Earth's crust as water evaporated from an ancient sea millions of years ago, Live Science notes.

The Hot Tub of Despair earned its nickname after the 2015 expedition members spotted crabs and various other creatures lying dead and “pickled” inside the cold seep. In fact, these animals are so well "embalmed" that their remains could remain perfectly preserved for decades, or even longer.

“These larger organisms really don’t like to be in this fluid — or maybe they just come here to die,” Scott Wankel, a marine chemist, said in a video of the discovery.

His colleague Erik Cordes, who co-authored a study on the extraordinary find, added: “We’ve known about [brine pools] for 30 years, [but] this one was pretty spectacular when it was found.

“It’s one of the coolest ones I’ve seen.”

The vast underwater pool lies some 3,300 feet down in the Gulf of Mexico(OET/NautilusLive )

The salty waters of the underwater lake result from the hydrocarbons bubbling up through the buried slabs of salt, according to Cordes' study, which was published in the journal Oceanographyback in 2016.

This brine is up to four times saltier than the seawater surrounding the seep, making it far denser and thereby preventing the two from mixing.

Water temperatures inside the tub reach up to 19C (66F) which, combined with the intense salt content, creates a deadly environment for all creatures, save for a few bacteria and some particularly sturdy organisms.

The brine also contains high levels of hydrogen sulfide and methane, which only the likes of mussels can tolerate. Indeed, mussels help to keep the steep "walls" which surround the pool intact.

These molluscs survive in the deep ocean thanks to a symbiotic relationship with bacteria that live on their gills. The bacteria use dissolved gases — such as methane and hydrogen sulfide — to make energy for them, as the Los Angeles Times notes.

The mussels that cling to the walls of the tub are fed by its mineral deposits, absorbed by bacteria living on their gills(OET/NautilusLive )

As well as cascades of mussel beds, the "walls" of the lake are encrusted with red, yellow and white mineral flows.

“You don’t expect to see [these bright colours] in the muddy background of the deep sea,” Cordes pointed out.

“It’s very weird. I think that’s what’s captured people’s imaginations. It’s such a bizarre kind of habitat.”

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