2.8 Million Eels Caught Hooking Up on an Underwater Mountain Named Patience, Which Is Exactly What Their Neighbors Ran Out Of

The ocean has kept many secrets. This week it admitted to the biggest one: a 3,500-tonne slow dance at the bottom of Tasmania, and nobody brought snacks.

A CSIRO-led study published in Royal Society Open Science estimates that about 2.8 million basketwork eels gather every year at Patience Seamount, an underwater mountain in the Huon Marine Park. That is roughly the population of Chicago, if Chicago were slimy, single and a kilometre underwater, which, to be fair, describes some of its Februaries.

Lead author Ben Scoulding, a CSIRO fisheries acoustics researcher, put it plainly: "It's the only known aggregation of … any deep-sea eel anywhere." Science has finally found the one club everybody goes to. No bouncer, no dress code, and a cover charge of 1,000 metres of crushing pressure.

The eels start arriving in December, peak from May to August, and leave in October. That is not a spawning season. That is a lease. Plenty of human weddings move faster, and most of them have a buffet.

Speaking of the buffet: researchers caught several eels and found all of them had empty stomachs. Millions of guests, ten months, zero dinner. It is the only party on Earth where everyone is too nervous to eat and nobody pretends otherwise.

Fishers, who are poets with worse hours, had nicknamed the spot Eel Hill. The mountain's official name is Patience, which is the most honest place name in the Southern Hemisphere. You do not wait ten months in the dark for romance without it.

To count the crowd, the team sent Australia's flagship research ship, the RV Investigator, to run hydro-acoustic surveys that Scoulding called a "really expensive scientific fish finder." "We're essentially pinging sound down into the water column," he said. Translation: the government paid a fortune to shout into the sea and listen for eels shouting back.

It worked because the eels have big swim bladders, and "Air is a really good reflector of sound," Scoulding explained. Somewhere, every man who talks too loudly at parties finally feels scientifically validated.

The crowd varies by neighbourhood. "The eels are almost touching each other in that centre part," Scoulding said. "And then the further you get out, it's almost like having one eel in a living room, so every 20 metres cubed." Downtown is a mosh pit. The suburbs are one eel on your couch, eating nothing and refusing to leave.

Then comes the real mystery. "It's one of 120 seamounts within Huon Marine Park … so it's quite unique that all the eels chose Patience to aggregate at," Scoulding said. That is 119 perfectly good mountains, and every eel in the region picked the same one. That is not biology. That is a group chat.

Researchers still do not know where the eels come from or where their babies go afterwards. Neither do most parents of teenagers, and theirs live upstairs.

The eels have now cleared out, as they do every October, hungry and presumably fulfilled. In December they will be back on Eel Hill, 2.8 million strong, still not eating, still almost touching, still proving that love at the bottom of the ocean takes exactly one thing. They named the mountain after it.