Workers of Hainan Power Grid Co., Ltd have brought the first of four planned seabed electric cables onshore at Linshi Isle in Chengmai, a county in China's southernmost island province of Hainan.

The 32-km-long 500-kilovolt underwater cable, the world's longest of its kind, was laid across the Qiongzhou Strait from Xuwen in Guangdong Province.

The cables, to be linked with the Fushan power transformer substation in Chengmai, are scheduled to be put into operation in April.

This is the second Hainan grid interconnection project launched by China Southern Power Grid, which will help double the power transmission capacity to the island to 1.2 million kilowatts.

The project is expected to significantly reduce the risks of a massive power outage on the typhoon-prone island.

Laying the cables is extremely difficult as the Qiongzhou Strait, with an average depth of 44 meters and a maximum of 110 meters, and which has complicated offshore conditions and high waves. The work for the first cable finished on Saturday.

"We sent robots to operate underwater to avoid errors and damage to the existing cables," said Huang Xianqiu, chief engineer of the project.

According to Huang, the work was closely monitored by professionals onboard ships.