Five extra limestone columns were found to be added to Victoria’s iconic Twelve Apostles after the discovery of researchers from the University of Melbourne and Deakin University during their sonar mapping of Victoria’s southern coast. They named these the “Drowned Apostles,” 60,000-year-old sea stacks located six kilometres offshore from the Great Ocean Road and 50 metres beneath the surface.

According to researcher Rhiannon Bezore, this is the first time that sea stacks submerged at this sea level have been seen. The study published in the Journal of Coastal Research explains that the well-preserved “Drowned Apostles” withstood the normal erosion rates in the ocean.

Computer imagery of the 'Drowned Apostles' -- limestone sea stacks found underwater off Australia's southern coast by Rhiannon Bezore.

Computer imagery of the ‘Drowned Apostles’ — limestone sea stacks found underwater off Australia’s southern coast by Rhiannon Bezore.

“Sea stacks are always eroding, as we saw with the one that collapsed in 2005, so it is hugely surprising that any could be preserved at that depth of water,” says David Kennedy, an associate professor from the University of Melbourne’s School of Geography. ”They should have collapsed and eroded as the sea level rose.”

The researchers used the latest multi-beam sonar technology. They believe that this new stacks used to be part of a larger limestone sea cliff just like the Twelve Apostles.

The Drowned Apostles adds to the diving experience when visiting the Twelve Apostles. These will also attract more tourists that will help boost the economy.

Kennedy asserts that the discovery shows that more undiscovered features that are still waiting to be found in the ocean. The researchers’ high-resolution sonar technology instrument would allow them to explore areas that have never been studied.

“People are only now with the technology being able to see the bottom of the sea floor in this detail,” Kennedy notes. “It’s almost like seeing an aerial photograph or looking at Google maps for the first time. So what we’ve really shown is how complex it can be, because these drowned landforms are also the habitats for a lot of our fish, lobsters and abalone.”