At low tide only 1 1/2 miles separate Kinmen island from communist China, but no one ever ventures down to the water's edge here as the sands are heavily mined on both sides. "If a cow wanders onto the beach it becomes instant roast beef," said an island resident, laughing. Visitors to the sub-tropical island content themselves with peering through military binoculars at China from inside a massive concrete bunker.
For 50 years the narrow stretch of turquoise and green water has formed the military boundary between Taiwanese territory and the mainland. It is likely to be the front line if war breaks out between China and Taiwan. Since President Lee Teng-hui of Taiwan declared in July that he would in future deal with China on a special state-to-state basis rather than as two parts of the same country, Beijing has made indirect threats to seize one of Taiwan's outlying islands in retaliation.
"We are naturally worried that China might attack and we are on the alert," said Kinmen's mayor, Mr Chen Shui-zai, whose office contains a four-foot model of a shell used by the US 7th Fleet to protect the island in the 1950s. "But generally the scene is calm," he added. "Farming goes on and the tourists are still coming."
Indeed, despite the crisis, Kinmen airport terminal at the weekend was full of boy scouts and other seasonal visitors from Taiwan, who arrive at the rate of 2,500 a day in summer to enjoy the unmined seaward beaches, to view the many beautiful relics of Ming and Ching Dynasty architecture, and to savour local seafood delicacies such as typhoon spirals and fried sand bugs.
The island is quite beautiful. It has two small towns and shady roads where blue trumpet flowers grow in profusion. At this time of year farmers spread sorghum across the surface to let traffic separate the grain from the chaff. Golden plovers and other exotic birds flash among the rowan and fir trees dripping with Spanish moss which have been planted everywhere by the army to hide tank movements.
A big attraction is the war museum, guarded by two old tanks, where rows of massive oil paintings tell the story of a 1949 battle when nationalist soldiers defeated an invading communist force which arrived on 270 fishing boats. The most prominent shows Gen Chiang Kai-chek inspecting victorious Kinmen soldiers from a jeep which is always coming towards the viewer, whether looked at from left or right.
"It's an optical illusion, just like the Mona Lisa's eyes," said the military guide proudly.
Since that battle, which ensured that Kinmen (once known as Quemoy), along with two other offshore islands, Matsu and Wuchiu, remained under Taiwan's control, the inhabitants have been completely cut off from their natural hinterland. Just across the water is the Chinese city of Xiamen, where many have relatives, including the survivors and descendants of 4,700 Kinmen people who, one night half a century ago, found themselves on the wrong side.
Xiamen is only half an hour's boat ride away but any of the 51,000 Kinmen inhabitants wishing to go there must travel via Taiwan and Hong Kong, a journey of almost 1,000 miles. It's the same with the mail.
At least it is peaceful now. In 1958 the island was subject to intensive artillery bombardment from China and for many years afterwards the two sides exchanged metal canisters packed with propaganda leaflets. Taiwan fired them across on Monday, Wednesday and Friday, and China on Tuesday, Thursday and Saturday; so that no one got hurt.
Until recently gigantic loudspeakers, the biggest in the world, blasted propaganda across the water but in the last few years the situation has quietened down - literally. The loudspeakers have been switched off and shell canisters are now used only as door stops or for making meat cleavers. The once-massive troop presence has been reduced to 20,000 soldiers, and the famous "831" military brothel (831 was its telephone number) has been closed, replaced by karaoke bars.
Some of the bomb-proof tunnels have been opened to tourists, including a vast sea channel dug into a granite hill big enough to take a dozen freighters at a time, which would make an ideal location for a James Bond movie.
Six years ago the island was transferred from military to civilian rule, and smuggling of goods and people across the narrow waterway has increased to the point where the mayor admits it is now out of control. Meat, fruit and vegetables come at night from the mainland.
Many Kinmen people are unhappy with President Lee for provoking Beijing's fury. Four out of five inhabitants support eventual reunification, said Mr Chen. "If Taiwan had a better relationship with China, then Kinmen would have a better future," he said. "I hope that Kinmen can become a neutral economic zone, a peaceful test area for closer links between China and Taiwan. Kinmen's future development should be connected with the mainland."
The island's civilian boss has a personal interest in a political solution. Taiwan does not allow mayors to go to the mainland and Mr Chen, whose family have lived on Kinmen for five generations, is the only islander unable to visit Xiamen. "Maybe some day we'll build a bridge across," he said wistfully. "But it won't happen today or tomorrow."