A sand tiger shark swims inside a tank. Enrique Calvo/Reuters Sharks attacked more than half a dozen surfers in North and South Carolina in a three-week period this summer — more than all of last year's attacks in those states combined.

The Carolinas weren't alone. A string of shark attacks has left some of Australia's most popular and best-known surfing beaches deserted, according to Reuters.

Experts say it's because this summer brewed the perfect storm for shark attacks: warmer ocean water, which attracts more sharks to shore, and more people than ever heading to beaches for a swim.

The solution is not to kill off more sharks — humans already slay 100 million a year just for their fins. That industry is already having catastrophic effects on delicate ocean ecosystems, and there's no reason to exacerbate the problem.

A more humane idea is to repel sharks. That's why an inventor has developed a $390 device surfers can embed in their boards to allegedly overpower the predators' delicate, electricity-sensing hunting organs.

Keep scrolling to see these high-tech surfboards and how they're supposed to work.