Four volcanoes have accidentally been discovered off the coast of Sydney, Australia. Put any ideas of a lava apocalypse out of your head though -- these guys are super old and unlikely to blow.
The ocean explorer vessel, the Investigator, stumbled upon the extinct volcanoes in June while looking into the baby-rearing habits of larval lobsters, according to Australia's national science agency, CSIRO.
The previously unknown land formation, more than 200 kilometres (124 miles) from the Sydney coastline and found 4,900 metres (3 miles) below sea level, is thought to be around 50 million years old.
The volcanoes may be ancient, but they're still big -- the largest is 1.5 kilometres (almost a mile) across the rim and has a height from the sea floor of 700 metres (close to a half-mile). In total, the caldera, a structure that is created when the land around erupted volcanos collapses to form a crater, is 20-kilometres long (12.5 miles) and six-kilometres wide (3.7 miles).
The exciting discovery gives scientists a peek at some of the hidden secrets under the Earth's crust. "They tell us part of the story of how New Zealand and Australia separated around 40-80 million years ago," Professor Richard Arculus, a volcano expert from the Australian National University, said in a statement.
"They haven’t been found before now, because the sonar on the previous Marine National Facility (MNF) research vessel, Southern Surveyor, could only map the sea floor to 3,000 metres, which left half of Australia’s ocean territory out of reach," he added.