Chu Jinyong finds his work as a diver challenging and interesting at China National Offshore Oil Corporation. Provided to China Daily

Most people dive underwater to appreciate the beauty of corals and various types of fish. But a special team in China's largest offshore oil and gas exploration company brave the depths to maintain and repair underwater drilling equipment and carry out offshore drilling platform construction.

They are called "frogman".

After serving in the navy as a diver for eight years, 35-year-old Chu Jinyong began his new career as a frogman in China National Offshore Oil Corporation in 2005. He is among 60 divers in the company.

"I love the ocean," he says. "Although many people consider my job as highly risky and I have to be away from my family for months because of this job, I still love it a lot."

Born in Hubei province and raised near the Yangtze River, Chu says his experience has taught him how to reduce risks and enhanced his underwater skills.

"As an engineer, diving is very different from our diving training in the navy," he says. "The training in the navy is for protection, which is more physical, while in the company, it is more technical and the aim of every task is very clear."

"Moreover, we have to consider the cost and return of each task. One mistake or a delay of the task can cause huge financial loss to the company."

As the national offshore oil company, CNOOC has the responsibility to explore new energy resources for this fuel-hungry country with rapid economic growth.

For a huge company with an annual crude oil production of about 3.4 million barrels, the team is always short of talent. Thus, the frogmen are always busy with many projects in areas where there is crude oil exploration.

The frogmen can work up to 260 days a year and Chu has already spent two Spring Festivals at sea.

"I was amazed by the advanced equipment when I first joined the company - many of which I had never seen before. And I knew that I have to start from the very beginning although I have been trained in the navy," says Chu.

His first task was to carry out flanges installation of an expansion bend for a drilling platform in Bohai Sea in 2006.

He was a member of the team and the leader did not allow him to dive by himself but asked him to help ensure the safety of other divers by monitoring in the control room of the ship. It was not what Chu had expected.

He tried to familiarize himself with all aspects of the work, from design drawing to project plans and professional tools, as well as taking notes of his observations, with the hope of being assigned to work underwater.

The team leader Chao Chunqiang who is three years older than Chu, told him that usually only an engineering diver who has more than three years' experiences can be allowed to work underwater for tasks such as flanges installation.

But Chu got his chance during his second year.

"It was in the winter and the sea water was freezing," he says. "I could not feel my hands after 20 minutes underwater, but I knew that I had to continue and finish the job."

After 50 minutes in the sea, Chu completed his first task as a frogman. But he later found out that it usually takes experienced divers 30 minutes to complete the same installation.

Chao told him that besides work experience, it is crucial to keep learning.

In 2008, Chu received supervising training for air diving, followed by healthcare and medical training for diving.

CNOOC has many overseas projects and the frogmen are sent to help on these. There are also foreign oil and gas companies with cooperation with CNOOC, which have sent teams to China for similar projects.

Chu says he has learned a lot from cooperating with his foreign counterparts from project operators like ConocoPhilips.

From July to December in 2009, Chu was working in a joint project between ConocoPhilips and CNOOC. Chu spent almost 100 minutes underwater for a complicated installation task, which had saved five to seven days' shipping schedule.

After eight years as a frogman, Chu says he has not thought about retirement.

"I have been grateful for the company's platform which has provided me lots of opportunities in this particular professional field," says Chu.