The Rolex “Sea-Dweller” was designed in collaboration with the famous French scuba diving company COMEX (Compagnie maritime d’expertise). In underwater missions, divers have encountered watch failure during decompression, when the glasses exploded due to an internal accumulation of air pressure. Rolex has modified the standard “Submariner” Ref. 5513 watches to include a helium escape valve to release air while maintaining the water-resistance of the watch. Thus, in 1967, the first Ref. 1665 “Sea-Dweller” watches were delivered to authorised dealers and selected divers for testing.