Five meters underground on the Taiwan Strait island of Kinmen, a dark concrete tunnel reverberates with sound of shelling.

But the noise of battle no longer drives the residents to their bomb shelters.

The sounds recreate the wartime footing that for long characterized relations between Taiwan and the Chinese mainland and now draws thousands of tourists from both sides of the Strait.

The tunnels, from a section of the civil defense facilities, have been converted into a museum, which gives visitors a vivid experience of the days after 1949 when the island was the frontline of the confrontation.

The museum's doorway is hidden beside the island's bus terminal. The main town looks so normal that it is hard to imagine it has a 9.5-km network of tunnels linking key government offices, the post office, school, bank, bus station and villages on the 132-square-km island.

"The tunnels were used to evacuate people. In addition, almost every household would have its own bomb shelter," says Huang Min-fang, a Kinmen native born in 1962, who grew up with the frequent shelling by both sides.

"Gradually people learned from the sound of the shells when it was time to retreat to the shelter."

The island maintained a large military garrison and a strict curfew until 1992. The buildings in the town were restricted to a height of three storeys. Lights-out was at 7 p.m..

"If we wanted to travel to the Taiwan Island, we had to go through a very complicated procedure of approval by the authorities, who feared infiltration," Huang says.

The shelling stopped in 1979. The Standing Committee of the National People's Congress (NPC) issued the "Message to Compatriots in Taiwan," published as a headline article in the Beijing-based People's Daily, on Jan. 1, 1979. It appealed for an end to hostile confrontation and tension across the Strait.

In 1987, the Taiwan and mainland authorities allowed civilians to visit relatives on either side.

The history of confrontation has become a tourist attraction on Kinmen. Military tunnels and bunkers as well as four sections of civil defense tunnels have been opened to the public.

One of the island's best-selling souvenirs is a strong spirit, made from a type of millet, produced by Kinmen Kaoliang Liquor, which uses former army tunnels as cellars.

The island, of 80,000 people, is 160 nautical miles from Taiwan Island and just 18 nautical miles from the mainland. It has become a bridge between the two sides.

In 2001, direct passenger and cargo shipping services began between Kinmen and the mainland's Fujian Province. To avoid flying via Hong Kong, as required at the time, many mainlanders took the boat to Kinmen and then flew to Taiwan Island.

Last year 1.28 million people traveled across the Strait via Kinmen and the number reached 710,000 in the first half of this year. A tourist guide for 15 years, Huang has seen great changes in her business.

"A decade ago, most tourists were from Taiwan Island, but now many are from the mainland," she says. "After mainland people were allowed to travel to Taiwan in June 2008, the number more than tripled."

Hong Bi-rong, a fisherman in Kinmen, travels to Xiamen, the nearest mainland city, several times a year with a multi-entry travel pass.

"I bought an apartment in Xiamen. I need to take care of it and also visit friends and family there. I've made many Xiamen friends in fishing," he says.

Lu Chih-hwei, chief secretary of Kinmen county government, tells Xinhua that Kinmen has played a role of "feeler" in cross-Strait relations.

"Many new cross-Strait policies are piloted here. We are honored to see the latest changes in cross-Strait relations," Lu says.

Although the two sides have operated direct flights and shipping services since late 2008, travel via Kinmen still has advantages, he says.

"Tourists can visit more destinations if they enter Taiwan via Kinmen and the travel cost is cheaper."

Kinmen University, established this month, is hoping to benefit from the trend by attracting mainland students.

Ten days ago, Taiwan legislature amended three laws to allow colleges to take students from the mainland. But the education department capped the number of mainland students at 2,000 each academic year.

However, Kinmen University will be excluded from the quota, and students from outside the island will enjoy the same tuition, courses and subsidies as locals, Lu says.