A video of fire spiralling upwards out of the ocean on Monday left authorities and social media users scrambling to understand the unsettling sight.
The flames were seen shooting out of the water in the Caspian sea overnight in videos shared widely online, giving the appearance the ocean was bursting with flames.
The most commonly shared footage was filmed from an offshore oil platform where workers could see the fireball shooting up from the horizon.
Azerbaijan's state energy company, SOCAR, said its offshore gas platforms in the Caspian Sea were safe after they were initially linked to the fire by local media reports.
On social media, people speculated about the phenomenon, with many suggesting it could've been the result of a mud volcano.
"I'm unclear which apocalypse we're up to now," joked one person.
"Captain Planet has had enough of our s***," another jested.
Early reports cited SOCAR as saying that an eruption of mud was the most likely reason for the blaze, although it did not explain how it could cause a fire.
"No incidents have happened at the offshore fields and industrial structures controlled by SOCAR, work continues normally," a spokesman said.
Truth behind viral ocean fire video
Amid the confusion, Mark Tingay, a mud volcano expert and associate professor at the University of Adelaide, was among those to correctly predict a mud volcano was behind the fiery explosion.
"Azerbaijan is the home of mud volcanoes, and has hundreds of them," he wrote on Twitter.
"And the mud volcanoes in Azerbaijan are some of the biggest and most violent in the world. There are, on average, several large mud volcano eruptions each year, and many of them can have big fires.
"The offshore region has lots of known mud volcano and mud volcano islands. They are islands because they've been able to erupt enough mud to poke up above the sea. Many others are submerged, or erupt to form 'peek-a-boo' short lasting islands," prof Tingay explained.
When the dust had settled, aerial footage ultimately confirmed it was a mud volcano eruption on Dashly Island.
It's an environmental phenomenon that scientists still don't fully understand.
The event came just days after an underwater pipeline leaking gas into the Gulf of Mexico set the surface of the ocean bubbling with fire as social media users only half jokingly made prophecies of doom.
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