A statement from the company said the final splice was carried out on Friday aboard the cable-laying vessel Ile de Brehat, at a point about 180km offshore Sydney.

The connected cable was then laid on the sea floor at a depth of 4865 metres.

The final fibre splice is completed. Courtesy Vocus

The fibre-optic system will deliver a minimum of 20Tbps capacity to both the Solomons and PNG. The system will have a total capacity of 40Tbps.

Vocus chief executive, Enterprise & Government, Andrew Wildblood, said: “The final splice on a subsea cable project is critically important and it’s exciting to have reached another key milestone.

“We’re very proud of the technical work our team continues to deliver for the Australian Government."

Engineers prepare the bight (slack) around the final splice. Courtesy Vocus

The deal to build the cable system was originally awarded to Chinese telecommunications equipment vendor Huawei Telecommunications.

The Solomon Islands then changed its mind after the intervention of the Australian spy agency, the Australian Secret Intelligence Service. Australian taxpayers have paid most of the $200 million cost of the cable, with the Solomons and the PNG making small contributions.

The contract was formally signed on 19 June 2018. The cable system also has a 730km submarine cable system connecting Honiara to .

Vocus said the Ile de Brehat would now head to Honiara to commence laying the Solomon Islands Domestic Network – a 730km fibre optic cable system linking Honiara with Auki (Malaita Island), Noro (New Georgia Island) and Taro Island.

Both the Coral Sea Cable System and the Solomon Islands Domestic Network are scheduled to be ready for service by the end of the year.