The water-resistant Nautilus ref. 3700
The case patent design of the first Nautilus, reference 3700/1, was registered on 23 April 1976. It comprises two parts, the main body and the bezel, at each side is an “ear” which couples with a corresponding flange, the two parts are secured by lateral screws. A rubber seal sits between the bezel and case body and is thus compressed when subject to water pressure forming a perfect watertight seal. From 1976 until 1980, the cases were made for Patek Philippe by Favre-Perret SA, Le Crêt du Locle.

In 1980, Patek Philippe launched the manufacture of cases and bracelets in their Ateliers Réunis workshops and the Nautilus changed its reference number to the new ref. 3700-11.