Photo courtesy of Ernie Tang

Fun Fact: Similar submersible watches were created for the Italian Navy by a Florentine watchmaking company known as Penerai. A top-secret operation, Panerai was the sole provider of measurement and precision underwater instruments in the 1940’s – including depth gauges, wrist compasses, detonators, sights, and large luminous waterproof wristwatches, similar to the one pictured above.