Rolex’s first commercially successful waterproof wristwatch case, introduced in 1926, was called the Oyster.
The Oyster case used a screw-down bezel, case back, and winding crown to help seal the movement against dust and moisture. Rolex founder Hans Wilsdorf presented the design as a major advance for wristwatches, which had often been vulnerable to water and dirt.
The name described the case’s protective principle: like an oyster shell, it enclosed the delicate mechanism. In 1927, Mercedes Gleitze wore an Oyster watch during her English Channel swim, giving Rolex a highly public demonstration of its water resistance.
The Oyster was a case design rather than a single modern model. Rolex later combined it with other innovations, including the self-winding Perpetual movement and the date display used by the Datejust. The Oyster name therefore appears across many Rolex families, while the Oyster Perpetual is also a specific collection.