What World War I technology was used to map the ocean floor?
Reconnaissance camerasReconnaissance cameras
5%SONAR, short for Sound Navigation and Ranging, uses underwater sound waves to detect objects and measure distances. Beginning in World War I, the technology was used to detect enemy submarines. Oceanographers still use SONAR to map the seafloor, measure water depths, and find shipwrecks. SONAR echoes, or soundings, are used to create 3D models of the ocean floor.
Source: NOAA