The Deep Diver, which emerged roughly around the mid-60s from Girard-Perregaux was not the manufacture's first waterproof watch. The Deep Diver was preceded by the Sea Hawk, a model name we are still familiar with today from GP's modern collection. The 1940s Sea Hawks drew their looks from military watches of the time and were housed in container-type cases to protect the movement from water (container case backs hold the movement, crystal and dial, while the upper portion of the case includes an additional pressure seal). These sporty timepieces aren't really true divers in the way we perceive watches today.
The screw-down crowns and rotating bezels that define dive watches for us today can be seen in Girard-Perregaux's mid-60s Deep Divers. These are attractive dive watches that are meant to compete with other famous divers from that era -- the IWC 812, Longines super compressor dive watch, JLC Polaris, and similar timepieces. The mid-late '60s Deep Divers are around 40mm and water resistant to about 600 ft., I believe. These particular models have the aforementioned rotating bezels and screw-down crowns, and are powered by the Girard-Perregaux caliber 32 family of movements. Dials and hand combinations vary across the Deep Diver models. My personal favorite model is reference 8953. That particular reference features a bakelite bezel inlay which has a tendency to crack. Many examples of these vintage Deep Divers that I've come across have damaged bezels. If you can find a ref. 8953 with an intact bezel in good condition, treasure it! 



