A Rolex Submariner watch is able to withstand depths of 300 meters (1000ft) due to its fitted Oyster case and triplock crown.
Rolex Oyster water-resistant case
Rolex patented Oyster case is fitted in all Submariner models. This is a determining factor for water resistance.
The Oyster case, invented by Hans Wilsdorf, was a revolutionary system where all the parts of the watch were screwed on to the case. Hermetically sealing the entire watch is another feature of the Rolex Submariner. The Rolex Submariner is kept watertight by the compression of the gaskets, just like a submarine hatch.
Rolex crown Triplock water-resistant
Water-resistant triplock crown is a feature that increases the water resistance of the Rolex Submariner.
Water-resistant watches have always been weakest at the winding crown. If the crown stem creates an opening in the case, it doesn't matter how waterproof the case is.
Manufacturers have faced a problem with this opening in their watch cases. Gaskets around the crown stem have been added to watch cases to prevent water from entering the case through the crown stem.
A third-generation water-resistant crown known as Triplock is available on the Rolex Submariner. In comparison to the Rolex Twinlock, the crown has larger and thicker gaskets.
Unlike the classic crown gasket, the patented triplock system on the Rolex Submariner gives better water-resistant than the many competitor's crown gasket. The watch has a threaded crown that screws down to the case, and a threaded stem crown has been added.
The Triplock crown is watertight in three zones. Waterproofness is guaranteed to 1000 feet (300 meters) depth with the addition of four gaskets and a thicker threaded tube.
If the Triplock crown is open, only one gasket is visible around the tube case. Two of the gaskets are attached to the stem inside the tube. During screwing down of the crown, the O-ring is compressed against the case for the best watertight protection.