A closer look
Decades before sonar became a slick Hollywood movie staple, early submarine communication relied on the highly sophisticated method of ringing underwater bells really loudly. During the 1903 Electroboat trials, engineers discovered that since water transmits sound faster than air, dunking a pneumatic bell over the side of a ship and listening through hull-mounted microphones actually worked. It was essentially a maritime game of Marco Polo, just with way more risk of drowning and zero subtlety.
