The current Oyster Perpetual is directly descended from the original Oyster from 1926. This was the first waterproof watch with which Rolex built its unprecedented and -based reputation. On 7 October 1927 Mercedes Gleitze swam across the challenging channel to England with the first waterproof wristwatch in the world. For 10 hours in a row, she bravely swam across the channel while the Rolex Oyster remained in perfect condition . Gleitze regularly read the watch to measure her progress and couldn't help but be under the impression of the fact that the watch kept ticking! After her swim, she said: "The Oyster I wore proved itself to be a reliable and accurate watch, all while being completely immersed in the seawater for hours."