The Oyster | The world’s first waterproof wristwatch (1926)
Launched in 1926, the Rolex Oyster was the world’s first truly waterproof and dustproof watch. To protect the dial and movement from elements, the Oyster was developed with a hermetically-sealed case, closed by a screw-down crown and screw-down caseback, each lined with rubber gaskets.
The following year, Rolex founder Hans Wildorf, famously gave swimmer Mercedes Gleitze one of the earliest Rolex Oysters to wear in her attempt to repeat her swim across the English Channel. After 10 hours in icy cold water, her Rolex was still dry inside.