Tran Island, part of the Co To District in northern Quang Ninh Province, is around 12-15 nautical miles from the delimitation line of the Gulf of Tonkin and is the furthest island from the shores of Quang Ninh. For decades, citizens and authorities have asked for the island to be connected to the national power grid.

To do so, underwater cables need to be connected from the mainland to the island. That is the job of 43-year-old Thach Thai Phong and around 20 divers, who have worked tirelessly every day since January to make sure the cables are properly laid.

The divers often split into two teams, each working six-hour alternate shifts no matter day or night. Equipped with scuba gear, they plunged the depths, connected to the surface by breathing tubes from barges floating above. A dive often consisted of two people, who worked for an hour before resurfacing to pass the baton to another pair.

Their job included checking the lights and cameras underwater, how deep the cables are and whether the robots are digging the seabed properly for the cables to be installed.

"If we encountered a rocky area where it wasn't possible to bury the cables, we would lay them open on the seabed and protect them with stone blocks," said Phong.

Thach Thai Phong, 43, in his diving suit ready to install underwater cables
to connect Tran Island in Quang Ninh Province to the national power grid.
Photo by VnExpress/Pham Tang.

Installing the cables to Co To Island was difficult due to the presence of rocky areas, according to Phong, having been among the first to install cables here in 2013. Doing so at Tran Island is much easier, seeing that rocky areas only occur about a kilometer away from the island, he added.

"The deepest parts we had to work on were 20 m below the surface. The sea in Quang Ninh has two clearly separated water flows, meaning it could be 30 degrees Celsius while you’re on land, but only around 20 degrees once you dive to the bottom. The temperature difference often sapped our strength," Phong maintained.

The most dangerous parts however are the shallow waters, about six to seven meters deep. At such a depth, divers are easily affected by noise from above, for example from passing ships. The noise could affect divers’ hearts, Phong explained. Several studies have suggested that exposure to loud noises may increase one's risk of a heart attack.

Deeper dives have their own risks as well. Breathing tubes and diving suits could be caught in objects underwater without divers being aware. In worst case scenarios, oxygen support could be cut off, Phong stressed.

Ngo Minh Vuong, head of the unit responsible for the underwater cable project, said the cables would span over 13 km underwater, connecting a station in Mong Cai Town with Tran Island.

Around 100 workers, including 20 divers and numerous ships, bulldozers, and other machines and equipment are enlisted for the project, Vuong added.

"We work 24/24. The project went well as we managed to avoid storm season. The most important thing is smooth coordination between divers and technicians on barges at the surface," he said.

A worker handles an underwater cable to connect Tran Island to the national power grid.
Photo by VnExpress/Do Phuong.

Cable cores were manufactured and tested in Spain, before the cables themselves were completed in Norway. They also have black and yellow ribbons wrapped around them as camouflage against sea creatures that may attack them, Vuong added.

All efforts paid off when the island, inhabited by 12 families, became part of the national power grid on September 2. Now, residents no longer have to deal with noisy power generators.

Nguyen Thi Canh, a local leader on Tran Island, said she and her husband were the first to come to the island in 2006. She recalled having to stumble in the dark with oil lamps to do the most basic of tasks, until more people came to the island and power generators were employed.

"Now that we have the power grid, we would no longer need to use generators, so it would be cheaper," she said.