Authorities in Sanya are telling sun-loving nudists to either cover up or get locked up.
The island's beaches on Hainan have for years attracted a set of sunbathers, mostly older men, who strip down to better soak up the rays, which they feel have restorative powers. While public nudity is traditionally frowned upon, enforcement has never been consistent.
But on Thursday squads of urban management officers and police could be seen trudging through the sand at Dadonghai beach, about three kilometres from downtown Sanya, handing out notices that offenders faced up to 10 days in detention.
"Most people have followed our advice and wore at least their shorts," said Xie Wanfeng, a spokeswoman for the Sanya City Administration law-enforcement bureau.
"There are around 200 people who regularly visit the beach. Most of them are middle-aged or elderly men from the northeastern provinces," Xie said. "Some of them stay on the beach for a whole day, and even eat their lunch there.
"Many of them are suffering from skin diseases and believe sunbathing can help them. But we have received many complaints from tourists who view it as an embarrassment."
The beach doesn't have any permanent warning posts telling people to cover up. Former Sanya mayor Lu Zhiyuan previously ruled out the possibility of establishing a nudist beach at Sanya.
"We have talked with them many times, but they seemed reluctant to change. We had to seek help from local police as we don't have the power to ban nudists," Xie said.
According to mainland law, local police can detain people who intentionally expose their bodies in public. Those who refuse to co-operate are subject to punishment of five to 10 days' in custody.
Wu Kaiyong, a security manager at the nearby South China Hotel, said most of the nudists agreed to put on their shorts yesterday. "Years before, when I saw them for the first time, I didn't find it acceptable, but I have now got used to it."
Nudist beaches have long been a controversial topic on the mainland. Luan county in Hebei province announced in June it would set up a nudist beach as part of a business development plan but is yet to follow through with the idea.