Submarine snorkel

A submarine snorkel is a device that allows a submarine to operate submerged while still taking in air from above the surface. It was invented by the Dutch shortly before World War II. One such device was captured and copied by the Germans during in 1940, and was adapted for use by U-Boats in 1943.

Submarine snorkel in The War That Came Early
The Submarine snorkel was adopted by the German Kriegsmarine in 1939, still in the early days of World War II. The device was originally a Dutch invention, and had been captured by Germany after it had overrun the Netherlands in the closing months of 1938. The device was first tested on the U-30, much to the horror of the u-boat's commander, LT. Fritz-Julius Lemp. Lemp, who thought the snorkel looked like an erect penis, complained bitterly to the engineers who installed it. However, Lemp relented when he learned that Admiral Karl Dönitz had specifically ordered it installed on the U-30 first.