What is the name of Rolex's triple waterproof crown system?

Rolex’s triple waterproof crown system is called Triplock.

The Triplock system is a screw-down winding crown designed to provide additional water resistance, particularly on Rolex professional diving watches. Its name refers to the crown’s triple-gasket sealing arrangement, which creates multiple barriers against water entering through the crown tube.

A Triplock crown is commonly identified by three small dots beneath the Rolex coronet on the crown. That marking helps distinguish it from Rolex’s Twinlock system, which uses two sealing points and appears on many less specialized models. Glidelock and Oysterlock are different Rolex features: Glidelock is a bracelet-extension mechanism, while Oysterlock refers to a safety clasp.

The crown is part of a broader waterproofing design rather than a standalone guarantee. It screws into the case, compressing its seals, while the Oyster case, crystal, case back and other components contribute to the watch’s overall water resistance. Divers should still follow the manufacturer’s instructions and never operate a crown underwater.