In his remarkable memoir of his life chasing breaks in far-flung corners of the globe, Barbarian Days, the writer William Finnegan describes the “spooky duality” of waves, the way that, “when you are absorbed in surfing they seem alive. They each have personalities, distinct and intricate, and quickly changing moods, to which you must react in the most intuitive, almost intimate way – too many people have likened riding waves to making love. And yet waves are of course not alive, not sentient, and the lover you reach to embrace may turn murderous without warning.” This idea of duality is...