Polcie are on the hunt for the vandals who broke in and damaged the treasured, 440 million-year-old Yarrangobilly Caves near Tumut.
On Saturday, officers from Riverina Police District began their investigation after reports of damage inside a cave within Kosciuszko National Park.
Investigators have been told between October 17 and 23, Jillabenan Cave which forms a part of the Yarrangobilly Caves was broken into and the stalactites and speleothems (straws) inside the cave were damaged.
A NSW Police statement said a padlock securing the doorway into the cave was removed, and the power distribution board was also damaged.
It also said the stalactites and "straws" within the cave are naturally formed, meaning that the damage is irreversible.
"It's just a terrible shame, I don't understand why anyone would do this," one of the staff members said.
The walks around the area and the thermal pool have been accessible but the three "show caves" and the deeper internals of the Yarrangobilly Caves have been closed during the COVID-19 pandemic period and are now slowly being assessed for reopening.
The self-guided South Glory is the only cave currently open to the public but more are expected to open in time for the coming summer holiday period, when the area is hugely popular with visitors.
The 12km cave complex was discovered in 1834 by a stockman.
Anyone with information or who may have seen anything suspicious in the area is urged to contact Tumut Police or Crime Stoppers on 1800 333 000.
