In a muddy camp ground surrounded by the vast greenness of northeastern Thailand's Khao Yai national park, scented candle seller Paul smiled with relief when seeing streams of tourists entering the park deserted due to COVID-19 for months.

The 30-year-old was invited to the "Stress Free Festival" in one of the most visited national parks held by the country's tourism body.

"I started my business six months ago, the time when COVID-19 broke out. I can't afford to rent a shop front," said the man who set up a lovely stall displaying home-made scented candles with different aromas against the backdrop of a fresh forest.

"I sell online. To my surprise, the sales volume is threefold of my goal," Paul told Xinhua.

"I'm glad to see people travel again, much more beyond my expectation. The festival and the long holiday drive tourists here. It's a good chance to set up a booth here to promote my products," said the man with a black mask, yet his smile could be read in the eyes.

The festival during the Songkran (Thai new year) holiday was packed with concerts, cloth mask fashion shows and workshop activities as an effort to boost local tourism.

Thailand's tourism industry had previously been buoyed by foreign tourists. But the government has been halting international passenger flights to prevent the spread of COVID-19 since April.

In an unprecedented scenario of no foreign tourists, the government has devised campaigns to fill the void and to encourage Thais to travel as much as possible inside the country.

Nestled in the lush, mountainous getaway destination of Khao Yai, a mango orchard saw a temporary tourism boom after a two-month closure due to the coronavirus pandemic.

"Bookings return. We have guests every day, especially during holidays and weekends, though the mango season passed," said orchard owner Waraporn with a bright, contagious smile.

"It happened to be the harvest when we closed," she said, showing Xinhua some tiny baby mangoes in the tree.

"We make the surplus into mango products, such as honey and dried fruits. We've been trying to use agriculture technology to ensure productivity as we open for tourists again after the mango season," said the owner whose family business narrowly pulled through without dismissing any of her staffs.

"Online sale and domestic tourism boost help a lot. It's an undoubtedly hard time, we hope economy activities pick up soon," said the always-smiley owner.

For Wipa, a hotel owner in southern Thailand's once bustling island destination Koh Pha Ngan, the pandemic has wiped smiles from her face.

Compared to Khao Yai which is just three hours drive from the capital city Bangkok, the island sitting at the Gulf of Thailand that takes a one-hour flight from Bangkok faces a bleak outlook.

Wipa said her hotel saw occupancy of only 10 percent during the four-day holiday since Sept. 4.

Wipa has been running the hotel for 30 years. "We have 124 rooms and more than 90 staffs. The revenue falls to less than 200,000 baht (about 6,700 U.S. dollars) monthly since March. About 90 percent of our customers are foreigners."

Best known for the boisterous night celebration "the Full Moon Party" and barely developed beaches, Pha Ngan Island is a tropical paradise for foreign tourists. The costly flight fare and accommodations often keep local tourists away from the island.

"The pandemic cuts off our income. We hope tourism rebound by the end of the year, or we may face closure," said the owner with a bitter smile.

In a country known as the Land of Smile, Thais have built an admirable reputation for making life fun and easy-going, and the smile is a key ingredient.

Though the country's tourism-reliant economy has been battered by COVID-19, Thai smiles have never lost out to the pandemic. However, something is missing.

"We have two foreign tourists since the lockdown measures eased. A Cambodian on his private jet using a long stay visa, and an ex-diplomatic personnel from Mexico who is an elite card holder under special arrangement", said the governor of the Tourism Authority of Thailand (TAT) Yuthasuk Supasorn with a wry smile.

Thailand welcomed more than 39.8 million foreign tourists last year, equivalent to half of the country's population. The TAT predicted the number of international arrivals this year may plunge 80 percent, with international air traffic regaining just 10 percent of the pre-pandemic volume.

In order to help the ailing tourism sector and save millions of jobs, the government plans to reopen the resort island of Phuket in the south as a model to welcome back foreign visitors.

However, the governor said the plan has hit a snag after the country recently saw the first case of local COVID-19 infection in more than three months.

He said stringent quarantine measures, divided local opinions and the capacity of medical service are factors to consider, which will set back the Phuket reopening plan.

"As a result, we need to focus on domestic tourism boosting plans. But we found domestic travel less than robust despite of government subsides. People still prefer short trips within three hours drive. Many destinations couldn't enjoy the tourism income," said the governor.

In addition to domestic tourism stimulus, the TAT tries to offer the two million expats in Thailand special travel deals. At present, the agency partners with Alipay and Fliggy -- a travel platform from China -- to promote domestic tourism campaigns for Chinese expats.

"We believe the pandemic will pass, the tourism boom will return someday. However, we don't know how many business can survive by that time," the governor gave a sad smile.