The United Kingdom and Norway have completed the construction of the longest submarine high-voltage cable in the world after about six years.

The North Sea Link has a length of approximately 720 kilometers and should make it possible to exchange renewable energy, reports Norwegian grid operator Statnett.

"If the wind blows in England and a lot of wind energy is produced, we can buy electricity cheaply in Norway from the British," said Statnett's project leader.

"And if there is little wind and high demand for electricity in England, they can buy hydroelectric power from us."

The cable is completely under water except for a few kilometers and connects the Norwegian Suldal with the British Blyth.

Construction is estimated to cost between 1.5 and 2 billion euros.

It was accompanied by a number of technical challenges.

For example, a more than 2 kilometer long tunnel had to be drilled.

Also, a special vessel had to be built for the work in a Norwegian lake.