Sonar
Sound Navigation and Ranging—a technique utilizing acoustic wave propagation underwater to navigate, communicate, or detect objects.
Governing formula
d = v_water t / 2
SI unit
m
In depth
Active sonar emits acoustic pulses and measures echo return delay; passive sonar listens silently to underwater acoustic noise.
Examples in the real world
Submarines mapping seafloor topography or fishing boats using echo sounders to locate fish shoals.