1922
Rolex Submarine
The Photos below feature a hermetic Rolex 'Submarine' watch made in 1922. Note, it's NOT named 'Submariner', but 'Submarine' as it was based upon the same principle as a Submarine hatch that would spin open and closed like a jar lid. It was called a 'Hermetic' watch as this new style of watch completely protected the entire movement, and notice, when it is sealed the watch winding crown, is hidden inside the watch. This case design was originally patented by Jean Finger in 1921, and Hans Wilsdorf later purchased the rights to the patent.
1922 Rolex Submariner
Think of a Hermetically sealed watch as being very similar to a jar lid (with a round glass aperture window) screwed on a jar. Once the lid is screwed into place, it forms an impervious barrier. No liquid can get in or out of the jar when the lid is securely screwed into place. (This, of course, is if you do not submerge the watch in deep water. At some point, without a gasket the case would fail and let water in). In many ways the Rolex Submarine was the great grandfather of the Rolex Submariner which Rolex would bring to life three decades later.
This page below shows Rolex's trademark for THE SUBMARINE, which was first registered in 1922, most fascinatingly by Rolex Founder, Hans Wilsdorf, himself!
The absolutely fascinating trademark page above and below are from the Swiss Journals E-Periodica and the one below features Rolex trademarks from 1938-1939, including the ROLEX AQUA, ROLEX RANGER, ROLEX SUBMARINE, and THE TUDOR. It's also worth noting in the bottom left hand corner there is a trademark from December of 1938 that is named "SOUSMARINE", which is French for "Submarine".