Extinct volcanoes discovered off Sydney

Extinct volcanoes, likely to be 50 million years old, have been discovered approximately 250 kilometers off the coast of Sydney.

University of New South Wales marine biologist Professor Iain Suthers, chief scientist on Australia's latest voyage for Australia's scientific body's research vessel "Investigator," said that while searching for the nursery grounds for larval lobsters the ship was also routinely mapping the seafloor when the volcanoes were discovered in 4,900 meters of water.

"The voyage was enormously successful," Suthers said in a statement on Monday, noting the discovery of seasonally unusual eddies off Sydney providing a hotspot of lobster larvae on July 7.

The four extinct volcanoes in the cluster are calderas -- approximately 20 kilometers long and six kilometers wide -- formed after a volcano erupted causing the land around them collapsed. The largest crater is reportedly 1.5 kilometers across the rim, rising 700 meters from the sea floor.

Australian National University igneous petrologist Professor Richard Arculus said these particular type of volcanoes are really important to geoscientists, providing a window into the sea floor.

"They tell us part of the story of how New Zealand and Australia separated around 40-80 million years ago and they'll now help scientists target future exploration of the sea floor to unlock the secrets of the Earth's crust," Arculus said.

The Australian scientific community's previous research vessel "Southern Surveyor" could only map the sea floor to 3,000 meters, leaving much of Australia's ocean territory uncharted.

"On board the new Marine National Facility vessel, Investigator, we have sonar that can map the sea floor to any depth, so all of Australia's vast ocean territory is now within reach, and that is enormously exciting," Arculus said.

Suthers said Investigator has other capabilities that marine scientists in Australia have never had before, and the vessel will be key to unlocking the secrets of the oceans around our continent and beyond.

"This is the first time [due to the new capabilities] we've been able to respond directly to the changing dynamics of the ocean and, for a biological oceanographer like me, it doesn't get more thrilling," Suthers said.

The research voyage led by Suthers departed Brisbane on June 3 and concluded on June 18 in Sydney. Endi