The tours have shown steady growth of around 10-20% annually despite economic stagnation and political crises, said Chartchai Pothipatcha, a consultant to the Association of Thai Tour Operators (ATTO).
''In more than 30 years of tours, the dhamma tour business is never down,'' he said.
Mr Chartchai, who is also the managing director of Thammajaree & CC Tour, said the bigger the crisis, the more dhamma tours grow because people look for moral support to lift their spirits.
He himself struggled to survive past economic crises. But he found religion as a universal remedy as it cures not only his spirit and business but also other people who are in trouble.
During previous slumps, he almost closed his business because of big losses from the outbound tour business. He was in trouble and feeling stressed.
But as he studied Buddhism and found moral support, it led him to the idea that others could likewise benefit. He started dhamma tours and his business gradually recovered.
Mr Chartchai said there have been more than 100 tour operators in this business during his time and only 10 or 20 were serious dhamma tour companies.
His company has more than 8,000 members now. Around 30% of customers for dhamma trips are repeats and 25% are teenagers and working people.
''Many people may believe dhamma tours are only popular among the elderly. In the past, this was true, but today the trend is changing. Teenagers and working people are interested in these tours because they feel pleasure and peace, which is different from other package tours,'' he said.
Average tourists per trip are 30 to 60 and will reach 200 during the beginning of Buddhist Lent. Total spending per head is 1,000 to 5,000 baht per trip.
For the local market, Mr Chartchai said popular destinations are the Northeast, the North and Central regions, respectively, while the South is unpopular because tourists still view it as dangerous.
''Buddhism rail routes in India are most popular for outbound markets. Sometimes customers must make reservations in advance of a year. Burma, Sri Lanka and China are becoming popular as well,'' Mr Chartchai said.
Although the dhamma tour business is quite popular now, tour quality can be a problem because of a lack of experts in Buddhist history and religious ceremony. Generally, tour companies add only ''Wai Phra'' (pay respect to Lord Buddha) into their packages.
In fact, Mr Chartchai said real dhamma tour companies should offer meditation practice, in-depth dhamma history education and a traditional religious ceremony. Tourists can pray, donate and study Buddhist precepts.
Retiree Angkana Srisuksakul said she would take a dhamma tour when she had free time because she can make new friends who love and believe in the same thing.
''I never took an interest in Buddhism until my close friend asked me to join one dhamma trip with her. My thoughts have changed since then. Buddhism makes me feel happy, peaceful, and emotionally secure. This is good for me and the people around me too,'' Ms Angkana said.
A student at Thammasat University, Sasiwan Boonsom agreed. She said Buddhism had changed her life and mind.
''I had to take a dhamma trip to accompany my mother and I thought it would be boring. Everything differed from my preconceptions as it was the best journey. I have better concentration after trying meditation during the trip,'' Ms Sasiwan said.
Now she must beg her mother to bring her when she takes a tour.
