The great success of the Bivouac inspired Favre-Leuba to employ the principle of the aneroid barometer to pressure measurement underwater as well: In 1968, the brand introduced the Bathy, the world’s first mechanical wristwatch that displayed not only dive time, but also the current depth. Two models were introduced, one measuring the depth in meters and the other in feet. This model shown here measured the depth in meters, up to 50 m.
Dive time can be adjusted and monitored using the rotating bezel with 60-minute graduations and the minute hand. A diaphragm inside the case transmits the pressure changes underwater to the red hand of the depth gauge, which indicates depths up to 50 m on the outer dial scale. On ascent, a red scale on the dial supports the diver in keeping within the necessary decompression times. The numbers and hands of the Bathy have extra-high luminosity, so that they are easy to read without error even in poor visibility conditions.