No boats, no surfboards, no kayaks—you just swim, scramble and jump to explore these rocky coastlines. Kerry Christiani heads to the birthplace of coasteering on Wales’ craggy coast and dives right in.

I didn’t intend to throw myself off a cliff. It just kind of happened.

I am standing on a rocky ledge, looking out onto the thrashing Atlantic. It is glinting an astonishing shade of turquoise in the pale June light. But there is little time to absorb the beauty of my surrounds. It’s crunch time.

Our guide Megan gives me a little nod and an encouraging smile. I hesitate. The cliff is only 10 meters high—which sounds like a doddle—but 10 meters might as well be 100 meters when you’re hurling yourself into the void, with nothing but you and the swirling torrent far below.

“I’m not sure I can do it,” I waver, as I inch slowly and shakily towards the precipice, holding back the expletives. “Ah, sure you can,” says my guide Megan, brimming with enthusiasm. “Keep your arms flat to your chest and face the horizon. “No,” I say. “I’ll wait a while and watch the others.”