The country's favourite mudstone attractions are getting some unwanted new features, Moeraki locals say.
A six-month surge in people carving names and words into boulders and leaving behind their rubbish has prompted calls for better management of the increasingly popular site.
Lesley Campbell, who has lived in the coastal town for 30 years, said the problem was not new, but seemed to have ramped up over the past six months.
On a recent trip to the beach, she said almost every boulder had been defaced, and she was able to intercept a group who were about to carve into one of the softer boulders near the cliffs.
"I think it's really disrespectful to the boulders, it's disrespectful to the people who live in the area, and it's disrespectful for people who come to visit," she said.
Though the sea had since washed some of the damage away on the softer rocks, Ms Campbell said she would expect better for a site advertised as the district's "flagship tourist destination."
The problem was also noticed by a recent visitor to Moeraki, Lauren Flutey, who said people seemed to be honing in on the soft, newly formed boulders.
As well as the vandalism, she said there appeared to be rubbish and cigarette butts being dropped "left, right, and centre" around the boulders.
"A bit more respect for them wouldn't go amiss," she said.
The boulders are on Department of Conservation (DOC) land and better signage was something it was happy to consider, by working with Te Rūnanga o Moeraki.
Coastal Otago operations manager Mike Hopkins said the behaviour was disappointing, disrespectful, and illegal, so DOC wanted to take a proactive approach.
"As the boulders rest on a public beach, it is challenging to monitor and protect the boulders and we do rely on the public to let us know if they notice any new damage," he said.
"We'd like to meet with the Waitaki locals who have recorded the vandalism and discuss potential solutions to monitor and prevent further damage."
Waitaki District Council chief executive Fergus Power said he had also been made aware of the vandalism issues, although it was somewhat inevitable for a natural feature tourism site.
He said the council would be working with DOC to increase awareness and help deter the taggers, including promoting the penalties of imprisonment up to five years, or a $100,000 fine.
"So those people who have found it irresistible to attack and deface the boulders probably were unaware of those penalties," he said.
"We'll be working with the Department of Conservation to raise awareness; firstly, of the inappropriateness of defacing national treasures, but also the severe consequences."
The numbers of tourists visiting the site isn't set to decrease anytime soon, with the boulders becoming a part of the Waitaki Whitestone Geopark.
One of the trustees, Helen Jansen, said they would be better informed, better educated visitors.
"We're all about promoting sustainability and getting that message across about the significance of the district and its geological history," she said.
She said signage panels were already being developed to better tell the story of Waitaki's many tourist sites.
However, Ms Campbell said if the area was going to pursue geopark status then it needed to demonstrate it could protect the resources it has.
DOC's asking locals to take photos if they see boulders being vandalised, and report them via its phoneline (0800 DOC HOT) or by visiting the Dunedin DOC office.