A Helium Escape Valve is a feature in dive watches that allows helium gas to escape from the watch case during decompression, preventing damage to the watch.
A helium escape valve is a one-way valve in professional diving watches that allows helium gas to exit the case during saturation diving decompression. During extended saturation dives, divers breathe a helium-oxygen mixture. Tiny helium molecules penetrate the watch seals over hours or days. Without an escape valve, the accumulated helium would violently push off the crystal during rapid decompression.
No — helium escape valves are only necessary for professional saturation divers who spend days or weeks living in pressurized habitats. Recreational divers breathing standard compressed air will never encounter helium-related issues. Most dive watches sold to consumers have helium escape valves as a technical credential or marketing feature, not out of practical necessity for recreational diving.
Professional dive watches designed for saturation diving include helium escape valves: Rolex Sea-Dweller and Deepsea (automatic valve), Omega Seamaster 600/1200/2000, Doxa Sub, Seiko Marinemaster. Rolex patented an automatic valve (opens under pressure, closes afterward). Manual valves (like Doxa's) must be opened by the diver before ascent. Most require water resistance ratings of 300m or more.