"I think that this is a great idea with much potential," says Ulf Leonhardt at the University of St Andrews, UK. "One could really imagine protecting coastlines by arrays of cleverly designed concrete poles."

Such structures act like metamaterials, materials whose properties result from their structure not composition, and can be used to make invisibility cloaks for light, he says.

But Guenneau cautions that large structures like islands and coastlines are unlikely to become invisible anytime soon, because building the many small islands needed to protect one is such a big job.

"It's crazy – maybe only people in Dubai could do this," he adds, referring to the spectacular artificial islands built there.

Smaller structures such as offshore oil platforms would be easier to protect, he says.