In the 1920s, with the end of W.W. I and the onset of flappers, short hair, and corset-free dressing, swimwear evolved. It was no longer just for bathing but for swimming, and as it became more functional it also became more revealing. After W.W. II, in 1946, the French engineer Louis Réard introduced the bikini, naming the skimpy two-piece suit for Bikini Atoll, a coral reef where the U.S. was conducting nuclear tests. “The bikini is the most important thing since the atom bomb,” exclaimed Diana Vreeland, never one given to understatement. This exhibition in London explores the way design has shaped our relationship with water. —Elena Clavarino