Vandals etched crosses on the crumbling remains of the 180-year-old palace of a former Hawaiian king, the state Department of Land and Natural Resources said Thursday.

But unless the vandals are caught desecrating the sacred cultural site, there’s little conservation law enforcement officers can do, the department said.

Kaniakapupu sits in the forest of Nuuanu. It was the summer palace of King Kamehameha III and Queen Kalama and the first government building built in a Western style, with mortar and plaster, according to the state.

Kamehameha III died in 1854 after a 30-year reign, making him the longest-ruling Hawaiian monarch.

The site was also used as a heiau, or place of worship, for Hawaiian royalty, the state said.

Volunteers who preserve and restore the site discovered crosses carved into at least three of the inside walls several weeks ago, said Dan Dennison, a DLNR spokesman.

It’s not the first time the site has been vandalized, said Baron Ching, vice chairman of the volunteer group Aha Hui Malama O Kaniakapupu.

“They’re carving happy faces, all kinds of stupid stuff,” he said. “When you vandalize it or damage it in any way, there’s no way we can repair that.”

Kaniakapupu is closed to the public, but that doesn’t stop social media sites from luring people there by touting it as a scenic and leisurely hike.

When Ching and a state official recently visited the site, a family preparing for a photo shoot had spread a blanket over the top of a stone structure outside Kaniakapupu’s walls.

That’s culturally disrespectful, Ching said: “It’s entirely inappropriate to be climbing around this place.”

It’s considered one of Hawaii’s most important cultural sites, the department said.

Within the past month, the department also found etched marks on the walls under a newly restored fence surrounding Iolani Palace.

“It’s hard to understand how anyone thinks it’s OK, or pono, to draw or etch graffiti on any of Hawaii’s historical or cultural treasures,” said department Chairwoman Suzanne Case, using the Hawaiian word that can mean proper or righteous.

In May the state completed a yearlong, $1.5 million project to renovate and repair the more than 100-year-old ironwork fence and plastered wall that bounds the four sides of the Iolani Palace grounds.

The renovation work involved stripping all rust and paint from the more than half-mile-long fence and gates and incrementally removing them to an off-site location where the individual segments received a hot-dip galvanizing treatment and repainting that should protect them more thoroughly and for much longer, the department reported.

The Hawaii incidents are the latest examples of bad behavior in U.S. natural or historic areas.

In May, actress Vanessa Hudgens paid a $1,000 fine for carving into a rock in the national forest surrounding Sedona, Ariz.

Earlier this month, Casey Nocket, 23, pleaded guilty in a federal court in Fresno, Calif., to seven misdemeanors for an autumn 2014 painting spree at seven national parks including Yosemite in California and Zion in Utah.

She also admitted to defacing rocks at Crater Lake National Park in Oregon and Rocky Mountain National Park in Colorado.

Nocket used Instagram and Tumblr to document her trip and her graffiti-like work, which led to broad outrage on social media. She was sentenced to two years’ probation and 200 hours of community service.

DLNR is asking witnesses or anyone who has knowledge of vandalism to any historical or cultural site in Hawaii to call the statewide DOCARE Hotline at 643-DLNR.