TGN Western Europe is a 3578km submarine cable system connecting Portugal, Spain and the UK with a ring configuration. Submarine internet cables, also referred to as submarine communications cables or submarine fiber optic cables, are essential infrastructure that connect different locations and data centers to reliably exchange digital information at a high speeds. Use the controls at the top to play the animation or step through year by year. Interactive map of the world's major submarine cable systems and landing. Submarine cables have a long history starting with the first commercial submarine telegraph cable in the English Channel in 1850, closely followed by the first transatlantic cable in 1866 1.