Scientists exploring Lake Rotomahana say they are certain they've found part of the Pink Terraces on the lake floor.



The discovery was made using robotic underwater vehicles to map the bottom of the lake.



Data collected by them clearly showed crescent-shaped terraced structures in about 60m of water where the Pink Terraces were located prior to 1886. They were covered by a brownish lake sediment.



Underwater photographs showed terrace edges as well as lake floor sediments.



"The first sonar image gave a hint of a terraced structure so we scanned the area twice more and we are now 95 percent certain we are seeing the bottom two tiers of the Pink Terraces," said Project leader Cornel de Ronde, of GNS Science.



The Pink and White Terraces, once described as the eighth wonder of the world, were destroyed during eruption of Mt Tarawera on June 10, 1886.



de Ronde said the discovery came right at the end of the survey.



"We weren't expecting this at all.



"We started seeing these hard reflective structures and, bingo, this is what we found."



He said the scientists believed they had found the bottom part of the terraces.



"We've found part of the existing lake shore that was not known to exist before."



He said what happened to the top of the terraces was still a mystery. It was conceivable they were still there, covered in layers of mud and water.



de Ronde said the fact that part of the original lake structure was still there made it hard to believe the Pink Terraces had been completely destroyed.



The remarkable part of the discovery was that the overlapping structures, about one to two metres high, were clearly visible on the lake floor.

AS THEY WERE: Pink Terraces, Roto Mahana, 1886 by John Philemon Backhouse, Oil on postcard. Source: Alexander Turnbull Library, Wellington, NZ, G-452-3-2