[4][5] Panerai watches, designed and manufactured by Rolex SA, were worn by the frogmen of the Decima Flottiglia MAS in their operations during World War II.

[6] Giovanni's grandson Guido Panerai (1873–1934) expanded the watch shop "Orologeria Svizzera"[7] and took over his wife's family business, a mechanical workshop.

Panerai became an official supplier to the Regia Marina (the Royal Italian Navy), supplying a variety of technical equipment and precision instruments.

[16][17] Panerai offers watches across four marketing lines: Historic, Contemporary, Manifattura and Special Editions in runs of 500, 1000, 2,000 or 4,000 units; each with its issue number on the case back.

For example, in 2006 issued the 1936 California Dial Radiomir special edition, a reissue of the first Panerai model presented to the Italian Marina Militare with production limited to 1936 units.