How the Internet Crosses the Ocean

Almost everything you send across an ocean travels along the seabed, not through space. Undersea cables carry more than 99 per cent of international data. This video explains how a cable about as thick as a garden hose can carry that much: hair-thin glass fibres, light pulses, repeaters about every 70 km and power fed from the shore at up to about 15,000 volts. It tells the story of the 1858 Atlantic telegraph cable that went silent within weeks, shows how cables are surveyed, laid, buried and repaired, and follows Tonga's five weeks with almost no internet after the January 2022 Hunga Tonga-Hunga Ha'apai eruption. It also covers why 150 to 200 cable faults a year mostly go unnoticed, why tech giants now build their own cables, and what Swedish and Finnish authorities actually said about the Baltic Sea cable damage of 2024 and 2025.