Armed police have begun to patrol beaches in Sanya, also known as the Chinese Hawaii, as the resort city bans nude sunbathing and swimming.
"Police officers will patrol the public beaches, telling people to wear bathing suits, and can detain those who refuse to do so," Wang Yong, mayor of the city, told China Daily during the ongoing annual session of the provincial people's congress on Sunday.
Wang said nude swimming and sunbathing are uncivilized behaviors, which might disturb other beachgoers.
According to a notice released by the Sanya police bureau, people who insist on swimming or sunbathing naked will be detained for five to 10 days. Since Thursday, police have posted notices to this effect throughout the popular resort destination.
Police said surveillance cameras would also be installed on beaches.
Luo Baoming, Party chief of Hainan province, criticized the behavior as uncivilized and "against Chinese traditions and culture".
"Normal people wouldn't do such things," Luo said.
Nude swimming and sunbathing is not new to Sanya, but started in 2002 with less than 10 people then doing so to help cure skin disease, according to Wang.
In recent years, more people have come to Sanya for nude swimming and sunbathing. About 500 Chinese and foreign tourists visit the Dadonghai Scenic Area each day at peak times, local media reported.
During the seven-day Spring Festival holiday from Jan 30, many tourists and residents complained to local authorities that nude swimming and sunbathing should be banned, because the behavior is disrespectful of females and children.
Li Qing, a resident of Sanya, applauded the ban.
"I have a daughter. How can I explain to her if we pass naked men sunbathing at Dadonghai," Li told Xinhua News Agency.
A local tour guide, surnamed Wang, said it is "embarrassing" for her to encounter naked sunbathers, especially when she is with clients.
Sanya received nearly 710,000 visitors during the Chinese Lunar New Year holiday, up 25 percent year-on-year.
Many netizens said creating a nudist beach could solve the problem, but Mayor Wang said that is impossible for Sanya.
Lu Zhiyuan, director of the Hainan tourism development commission, said travelers should respect Chinese culture.
Kirmo Wilen, a photographer from Finland who traveled to Hainan during Lunar New Year, said he respects Chinese culture but nude swimming or sunbathing is not considered uncivilized in Western countries.
There are hundreds of nude beaches around the world, with the Leucate Plage beach in France ranked No 1 by lifestyle website www.therichest.com.
However, the concept of nudism is not widely accepted in China.
Many places, including Heilongjiang, Sichuan and Zhejiang provinces, have tried to create nudist spots since 2000, but all failed because of the huge controversy triggered.