Foo showing off a clown featherback; his black fish finder is seen attached to his kayak near his knee.
STRIKE a metallic object, and you’ll hear a sharp clang. Knock on wood, and you get a dull thunk. It’s the basic principle behind sonar – sound waves reflecting off different objects.
Anglers use sonar technology, too, in the form of a fish finder, which emits ultrasonic pulses into the water and “listens” to the echoes bouncing off objects below.
