Picture a landscape of jagged peaks and sharp valleys strewn with enormous boulders the size of small houses. This is the scene beneath the sea off the coast of Norway, where the world’s longest undersea gas pipeline begins its epic journey across the ocean floor to Easington on the eastern coast of England, 1,200km away.

The Langeled pipeline consists of tens of thousands of individual steel sections, each several metres long and around a metre in diameter. These are welded together on a special ship, a ‘floating pipe factory’, before a protective coating is applied and the pipeline is laid on the sea floor at a rate of up to 5km per day.

The seabed itself is prepared in advance, with underwater diggers removing boulders and levelling the terrain by dumping 3m tonnes of rock. When it is complete the pipe will carry more than 70m cubic metres of gas a day from the new Ormen Lange field in Norway to the UK.

Things have come a long way since the first gas company was founded in London in 1812. The first ‘long-distance’ gas pipeline (it was a mere 8km long and 5cm in diameter) was laid in Pennsylvania in the US in 1872.

Around the world today there are ambitious plans to construct new pipelines to carry natural gas across hostile terrain, such as the north of Canada, Siberia and the Sahara. New technology means that such projects are feasible, but security is a key issue. The recently opened Baku-Tbilisi-Ceyhan line is 1,760km long and runs from the Caspian Sea to Turkey. It has been buried along its entire length in order to protect it, adding hugely to its construction costs.