Taipei, Taiwan – On Taiwan’s sandy coast, Liu Xi Jiu puts on his goggles and prepares to race across one of the most dangerous bodies of water in the world.

The Beijing native is taking part in the only event of its kind, a seven-kilometer swim race through a geopolitical hotspot, from the Kinmen Islands off Taiwan to the city of Xiamen on China’s east coast.

Around him, 200 athletes from China, Taiwan, Hong Kong and Macau laugh and joke as they warm up. In front of them, behind the rows of anti-invasion spikes that line Kinmen’s golden beaches, Xiamen’s striking skyscrapers glitter in the morning sun.

But the warm weather and sense of friendly rivalry mask increasingly strained relations across the strait that separates democratic Taiwan from China, which claims the island.

As the swimmers prepare for the grueling 90-minute crossing, they hope their camaraderie can serve as an example for smoother exchanges in these choppy waters.

Kinmen and its people have always had a close relationship with China, Wu Zeng Yun, CEO of the Kinmen-Matsu Joint Services Centre, told Al Jazeera.

Although Wu’s workplace now serves as a local branch of the Taiwanese central government, the building still bears the name Fujian Provincial Government. The gold characters above the imposing entrance are a reminder of the time when Kinmen was part of China’s Fujian province.

“My uncles used to do business in Tong’an on the mainland,” Wu said, referring to the historic district that can be seen across the water from his office.

“It was a communal living area,” he added. “You just went to the pier, boarded a boat to Tong’an and paid the fare.”

But after the end of the Chinese Civil War in 1949, everything changed. Faced with defeat by the communists, the Nationalist government of the Republic of China fled Beijing and established itself in Taiwan, also retaining control of the Kinmen Islands, which lie more than 300 kilometers from Taipei.

The island’s inhabitants were cut off from the province to which they had once belonged and soon found themselves at the front of a political struggle between Taipei and Beijing that at times escalated into violence.

Because China regularly bombed the island until 1979, residents can remember hiding in bunkers scattered across the island and seeking shelter as bombs rained down on their villages.

China only reaffirmed its willingness to take control of Taiwan by force in a white paper in 2022, which it considers to be its own territory. The government in Taipei says the Taiwanese people should decide their own future.

Increased tensions

At the Shuitou Pier ferry terminal on Kinmen, lawmaker Chen Yu Jen said her father was on board one of the first boats that reconnected Kinmen with China in 2001.

At the time, it was hoped that such connections could help improve relations between Taipei and Beijing. But as Chen heads to the gate and prepares to follow in her father’s footsteps, that hope has not yet been fulfilled.

In mid-February, Kinmen was again at the centre of tensions between the two sides of the Taiwan Strait after a clash between the Taiwanese coast guard and a Chinese vessel caught fishing in the waters off Kinmen, resulting in the deaths of two of the fishermen.

To make matters worse, it turned out that the Chinese boat had capsized after colliding with the Taiwanese vessel, a fact that Taipei had initially concealed in its report on the incident.

In response, the Chinese Coast Guard, which is indirectly under the command of Beijing’s Central Military Commission, increased its presence in the region.

Looking out over the choppy waters from his small boat, local fisherman and business owner Lu Wen Shiung says the fishing community has already felt the impact.

“When relations between the two sides of the Taiwan Strait were less tense, we had good relations with the coastal fishermen from the mainland,” he recalled. “When the fishermen from the mainland caught a good catch, they shared it with us.”

But since CCG vessels have regularly entered Kinmen’s territorial waters – a limit that was largely respected until February – Lu now faces pressure from Chinese vessels even when his boat approaches Kinmen’s coast.

“The activities of the Chinese coast guard have changed significantly. They now patrol our waters regularly,” Lu explained.

In an unprecedented move, the CCG even boarded a Taiwanese excursion boat in February. Three months later, it announced for the first time a series of military exercises around Kinmen.

“When we go out to sea, we often encounter them,” said fisherman Lu, referring to the CCG. “I have already been followed three times this year.”

At the beginning of July, a Taiwanese fishing boat with two Taiwanese and three Indonesian citizens on board was confiscated by the Chinese coast guard and brought to the mainland. The accusation was that they had violated a summer fishing ban. The captain of the boat is still under investigation, but the crew was released this week.

“Some fishermen working nearby fear that any misstep could result in their boat being detained,” Kinmen district councillor Tung Sen Pao told Al Jazeera.

While analysts say China’s incursions are part of Beijing’s “gray zone” tactics to put pressure on Taipei, some on Kinmen worry about the potential risk of escalation and unintended conflict.

Recognition and respect for Kinmen’s closed waters is “crucial to maintaining peace,” said Wu of the Kinmen-Matsu Joint Services Centre. “If the mainland unilaterally refuses to do so, it increases the risk of conflict.”

“If border units, coast guards and coastal police clash during their operations, it could lead to unnecessary confrontations and accidents and possibly trigger military conflicts that would be detrimental to both sides,” said Councillor Tung.

Silver lining

Despite the uproar caused by the fishermen’s deaths, some are confident that Kinmen can once again become a place of cross-strait cooperation, pointing to a certain degree of “goodwill” between local governments on the island and in Xiamen.

On July 30, the Straits Exchange Foundation (SEF) in Taipei – a semi-official organization promoting cooperation between both sides of the Taiwan Strait – and its Chinese partners finally agreed to return the bodies of the Chinese fishermen to the mainland. Their deaths had led to the first tensions in February.

Now that the men’s bodies have been returned to China, some hope that the situation will ease.

A former Taiwanese soldier who was arrested in March after his boat entered Chinese waters was also released this month.

Back on the beach in Kinmen, Chinese swimmer Liu stands shoulder to shoulder with his Taiwanese competitors and looks out over the Chinese coast.

For him and many other Chinese swimmers, it is the first race in Taiwan.

Like the competition’s organizers, the swimmers hope the race will serve as an example of what can be achieved through cooperation and the diplomatic progress that has already been made.

“Sporting events of this kind promote connection between people,” he said. “I hope that both sides can resolve their problems peacefully.”

When the starting horn sounds, he plunges headfirst into the waves and races at full speed through the water on his way to Xiamen.

“The sea between Kinmen and Xiamen used to be a battlefield. They fought each other with bullets,” recalls MP Chen. When she was growing up, Kinmen’s coasts were strictly closed and reserved for military purposes.

“Now this sea is a place of peace. People can swim across and swim back,” she said.