There he was, silently gliding above the water like a commuter on a cloud.When Kai Lenny released footage of himself riding a self-propelled hydrofoil board, people were stunned and jaws smacked the floor. One Surfline reader commented: 

But while Lenny made the unconventional craft look incredibly fun, the boards apparently pose a serious threat to riders and others in the lineup. After watching the Maui waterman cloud surf, a well-honed wave-rider from Japan named Yu Tonbi Sumitomo wanted one for himself. “Got one foil from friend for myself,” Sumitomo wrote via Facebook. “Can't wait try this. look fun!!”

And fun it was, until the foil slashed Sumitomo in the face.

The injury and resultant photo showing a massive head wound sparked big-wave charger Jamie Mitchell to make a hydrofoil PSA. From his Facebook, Mitchell wrote:

So lately I have been asked consistently about my thoughts on the so called "NEW" foil popularity and haven't really said much. But, yesterday sadly I saw a photo that I new was coming sooner than later. In my opinion Foils are for open ocean swells, Outer Bombies, and places where there are no people or very few people doing it together. Foils are dangerous, very dangerous, and do not belong in the surf zone with the masses and general public. Yes, Kai and and a few talented kids can probably control the boards amazingly well, but you can't control other peoples’ actions and movements. I see more and more clips everyday of people trying the foils and I am so scared that someone will pay the ultimate price and die. Look at this photo below. If a foil hits you or you hit someone with the foil, it’s going to end badly. I sure hope the people and companies that are making money off these are doing their best to educate people about the dangers. I don't think this will be the 1st or last incident unfortunately. I’m very happy that the gentleman in this photo will be ok. Please think about your surroundings before you just jump in and start surfing those boards.

To be certain, surfing (in general) is dangerous. But incorporate a knife-like foil, slicing through the water, under your feet, and the threat gets even greater. It’s all fun and games until someone nearly gets decapitated.