Taming the 7,000-tonne 'sea dragon': Powering China's volcanic island

For years, Weizhou Island was an "electricity orphan." Located 24 nautical miles off China's coast, the volcanic island relied on noisy, limited diesel generators. That isolation ended recently with the successful laying of a massive 44.8-kilometer undersea cable – a 7,000-tonne "sea dragon" heavier than 80 freight cars.

The project's biggest win is technical independence. High-voltage submarine cables require specialized insulation to survive the crushing pressure of the deep sea. For the first time, this 220-kilovolt cable uses 100-percent domestically developed insulation materials, breaking a long-standing reliance on imports and ensuring a more secure energy supply.

To place the cable, engineers used the Dejing-106, a vessel equipped with a specialized underwater plow. This high-tech "farmer" uses high-pressure water jets to carve a trench 4.3 meters deep, tucking the cable safely into the seabed and covering it with sand in one seamless motion. Automated sensors acted as underwater eyes to prevent any damage during the 16-day operation.

Weizhou Island is a sanctuary for coral reefs and rare Bryde's whales. To stay eco-friendly, the team used directional drilling to tunnel 25 meters beneath the seafloor bypassing sensitive reefs entirely. Monitoring stations confirmed that water quality remained pristine throughout – in fact, 35 sightings of whales and dolphins during construction proved the "sea dragon" was a quiet, welcome guest.