Kelly Slater's Impossible, Unnameable Air: An Explainer

Today in Portugal, Kelly Slater pulled off an aerial maneuver never before completed on a surfboard. The only problem is no one can agree on what to call it.

Slater, who won his first World Championship Tour title before some of his competitors were even born, was freesurfing on a lay day when he raced down the line and launched and spun and somehow landed. You can actually hear the gasp from the filmer:

Another angle:

But after the footage of the maneuver was uploaded, the real debate began on what to call it. The Association of Surfing Professionals, which runs the Tour, called it a 720 on their YouTube video, but a 540 on their website. Several other surfing websites are calling it a 540, and USA Today, ever the fence-rider, asterisked it a 720, "or 540 (depending on which side of this debate you agree with)."

Those that are calling it a 720 are looking at it from the broader extreme sports perspective. On a skateboard or snowboard, a 720 consists of approaching the lip of a halfpipe with your dominant foot forward, spinning around twice, and landing exactly the way you came, riding backward:

By this definition, yes, Kelly Slater landed the first-ever 720. He started the air with his left foot forward, spun twice, and ended up with his right foot forward.

But surfers argue that surfing is not skateboarding, and instead of going up a wall like a skateboard ramp, surfers move across it. From this perspective, Slater spun around a complete 360 and then added another 180—therefore a 540. In fact, one of the first riders to try the maneuver, Australia's Chippa Wilson, insisted on calling it a 540 as he attempted it.

The one person with enough clout to settle the debate—Slater—never put a label on what he did. When asked, he said, "I don't have a name for it. It's an aerial."

Slater is currently ranked second in the world with two stops remaining in the WCT season. This air, whatever it's called, is just one more reason Kelly Slater will not die.