The Tourism Authority of Thailand (TAT) is concerned that Vietnam, a rising star in Asean, will draw more South Korean tourists away from the Kingdom.
Thailand is seeking to use its attractive travel prices and established infrastructure to lure South Koreans and tackle the threat.
South Korea is a top-five East Asian tourist market for Thailand, while Thai tourists are ranked fourth among outbound tourists to South Korea.
In 2015, South Korean tourist arrivals to Thailand grew 22% to 1.37 million, while Vietnam welcomed 114,740 South Korean travellers, a surge of 131%.
Siriges-a-nong Trirattanasongpol, director of the TAT's Seoul office, said the average hotel room rate in Vietnam was higher than in Thailand because of limited supply.
"Vietnam will be Thailand's key rival for the South Korean tourist market in the next five years. Its tourism infrastructure is developing so fast, its products are fresh and tourist safety is good. Moreover, Vietnam is an investment destination for South Koreans," she said.
The TAT has been creating new tourism products with the aim of improving market segmentation for females, families and incentives.
It aims to promote Thailand as a luxury camping destination. Camping is a popular activity among Koreans, who love outdoor activities and generally go with their families.
The TAT has worked closely with Thailand Convention and Exhibition Bureau to promote incentive trips by offering interesting activities in packages such as Muay Thai classes for groups of 100 persons or more.
Ms Siriges-a-nong said Vietnam was becoming a popular destination for incentive groups because it was new, especially as a beach destination. Meanwhile, many main beach destinations in Thailand have deteriorated.
The downgrading of Thailand's aviation standards by the International Civil Aviation Organization is also a key obstacle because tour operators cannot use charter flights, she said.
The TAT held roadshows in Busan and Seoul from June 13-15, taking 67 Thai tourism operators to meet travel agents in South Korea. The event helped operators to present their products directly to tour agents.
"Safety is a major concern. If Thailand can solve this problem, it will boost inbound tourism significantly, not only the South Korean market but also others," Ms Siriges-a-nong said.
The TAT is still confident that travelling in Thailand in more fun than in Vietnam, while the tourism situation is positive thanks to political stability.
It expects South Korean tourist arrivals to Thailand will record a high again this year after reaching 1.37 million last year. With the upward trend, arrivals from South Korea are expected to reach 1.5 million this year, growing 9.2% to outpace the previous projection of 4%.
As of May 31, tourist arrivals from South Korea to Thailand had increased 12.7% to 619,030.
Although the South Korean economy is slowing, its tourism business has been modestly affected because travel is part of people's lives as a way of escaping pressure.
The TAT expects arrivals from South Korea to Thailand will reach 1.8 million in 2020.