How Greece Built a World-Record Cable to Crete — Then Had to Lay a Second One 1,200m Down

Crete generated every kilowatt it used, in the same hour, on ageing units burning heavy fuel oil and diesel — no cable connected the island to mainland Greece. The first fix, energised in 2021, ran 174 kilometres from the Peloponnese and became the longest AC cable interconnection in the world, laid at a depth of 1,000 metres, for €380 million. It worked. It was not enough. Generation on the island sometimes cost more than €300 per megawatt hour. Island customers were charged mainland prices, so the difference came out of a Public Service Obligation charge spread across every electricity bill in the country — a household in Thessaloniki was helping pay for diesel burned in Heraklion. Push alternating current far enough down a cable and the cable spends its own capacity charging itself. So Greece changed the technology. Ariadne: 335 kilometres of HVDC, two cables at 500 kilovolts, reaching 1,200 metres of water, more than €1.1 billion. It entered operation on 24 May 2025, taking the combined capacity of the interconnection to 1,000 megawatts — together with Sardinia, the largest island interconnection anywhere in the world. Savings are estimated at around €400 million a year, and roughly 1.5 million tonnes of CO2 a year no longer burned. The lights on Crete were never the problem. The isolation was. CHAPTERS 0:00 The island that had to burn everything it used 0:48 650,000 residents, 5 million tourists 2:56 €300 a megawatt hour 3:33 The bill every Greek household was paying 4:39 Phase one: the longest AC cable in the world 7:03 Laying a cable a kilometre down 8:50 It worked — and it was not enough 10:49 Ariadne: 335 km, 1,200 metres down 12:58 24 May 2025 — the switch 14:37 What an island actually lacks #engineering #documentary #greece #crete #infrastructure #energy #megaproject #megastructure DISCLAIMER ____________________________________ This is not engineering advice. Everything here is for informational and entertainment purposes only. Contact an engineer licensed to practice in your area if you need professional advice or services. All non-licensed clips used for fair use commentary, criticism, and educational purposes.