A terrestrial cable has successfully traversed a pre-laid channel beneath the seabed on two islands in ocean waters north of the city of Zhoushan (part of East China’s Zhejiang Province), marking the completion of the first project of its kind in China.

Per multiple media reports, including China Daily, the terrestrial cable provided by the Hengton Group links the islands of Zhoushan and Shangyuanshan. The State Grid Zhoushan Power Supply Company, the project’s developer, said that inter-island energy transmission in China is usually done with submarine cables. However, China’s coastal waters have dense waterways and busy ships whose anchors could easily damage submarine cables, which led to using of a 10 kV one-km-long terrestrial cable that is buried deeper.

Li Zhen, the head of the design company of the project, said that other advantages include lower costs to make the cable as well as easier construction. To reduce tension and friction of the cable during the line laying, the company used wire rope traction, essentially installing an “exoskeleton” for the cable. It then used pipeline lubrication materials to reduce friction, ensuring that the cable remained intact during the dragging process.

Zhen said that this method could be “extensively applied to connect islands separated by short and medium distances of no more than 2 km.” The long-term goal, he added, is to achieve connections between islands over medium and long distances.