Mastering waterproofness. Almost a century ago, in 1926, Rolex unveiled the world’s first waterproof wristwatch, the Oyster. Thanks to an ingenious patented system consisting of a screw-down bezel, case back and winding crown, the case was hermetically sealed, thereby offering optimal protection for the movement. To test the robustness and demonstrate the waterproofness of the Oyster, the brand equipped swimmer Mercedes Gleitze with the watch for her swim across the English Channel. After more than 10 hours in the water, the timepiece was still in perfect working order. Over the years, the Oyster case evolved, integrating Rolex innovations and increasing its water resistance. Today, all watches from the Oyster Perpetual collection are fitted with the modern Oyster case, which is built on the same principle as the original.