It’s no secret that human activity has depleted coral reefs in some of the world’s prime vacation spots. Architect Wolf Hilbertz and marine researcher Tom Goreau are doing something about it—introducing electrified metal "reefs" in the damaged areas, which Goreau says can grow teeming coral nurseries in a matter of years, rather than decades. A slight current, sufficient to power a lightbulb, encourages the creation of calcium carbonate deposits—the primary building block of a natural coral reef—on the structures’ surface. So far, the artificial reefs have debuted successfully at the Maldives’ Banyan Tree Resort on Vabbinfaru Island and at Taman Sari on Bali. Divers take note: more than a dozen other locations are due to be plugged in next year.