Water shortage

A shortage of fresh water has also hindered the trees' growth. In 2008, desalination facilities were installed at the camp, but before then the water for both the trees and daily use came from a well.

"That water was no different from seawater," Qiu recalled, adding that on other islands, plants and deep sand filter some of the salt from the seawater, but on Zhongjian, where trees are scarce and the land is less than 2 meters above sea level, the water is barely filtered. Many sailors have contracted skin diseases after wearing clothes washed in the brackish water.

A decade or so ago, the only fresh water came from a twice-yearly shipment that was stored in two tanks that each held 150 metric tons of the liquid.

Zhang said that every morning after training, the sailors would line up in front of the tank and their captain would scoop a set amount of water into their basins so they could wash and brush their teeth.

The used water was supposed to be poured onto the vegetable plot, but some sailors secretly poured it on to the tree they had planted the day they arrived because it had a special significance for them.

"They place their hopes on the tree. Going to check their own tree every day and seeing it grow is a memory for them on the island," Zhang said.

Guo Danyang, leader of the radar squad, said, "These harsh natural conditions mean far more trees have been planted than have actually survived." Guo is Zhongjian's longest-serving inhabitant, having arrived in 2003.

"The survival rate of coconut trees is very low, and they take a long time to bear fruit. A normal coconut tree in Hainan province probably needs only half a year to produce a coconut, but here in Zhongjian, it takes at least 12 to 13 years. Some of those planted when I came to the island have yet to yield a single coconut," he said.

"In the early years we could see the coconuts, but were not allowed to taste them, because there were too few and there was no way to guarantee that everyone could have a mouthful."

Zhang remembers his first sip of fresh coconut water in 2012, when a few of the trees had started to yield fruit. One day, he received an order from the garrison captain to collect 22 coconuts over the following week, but the work had to be done in secret.

"You have to collect 22 coconuts, no matter what. They will be of great use to me," the captain told Zhang.

Zhang didn't understand what they would be used for, but he obeyed the order and placed the fruit in cold storage. On a Saturday evening after a physical training session, all 22 members of the garrison were relaxing, when the captain ordered Zhang to fetch the coconuts. He told the sailors, "Today we are going to complete a feat-everyone must drink a coconut."

Zhang said: "We each cut open a coconut and cheered. It was the first time I had tasted coconut since arriving. They were all grown by us. Even though they were small and tasted quite sour and rough, I still found the taste very sweet."