When a sonar works, it uses sound waves to detect and locate underwater objects or measure the distance to the seafloor. It can be used for

• submarine detection
• mine detection
• sea floor mapping
• commercial fishing

and all kinds of other water distance mapping things.

The most common sonar device sends out a subsurface sound wave and then listens for returning echoes. The sound data gets sent back to the human operators by a loudspeaker or a monitor display. Then someone can process the information (most likely using computer algorithms) to figure out what the scene looks like.

The word sonar comes from an American acronym for SOund, NAvigation and Ranging during World War I. The British call sonar ASDICS, which stands for Anti-Submarine Detection Investigation Committee.

But…sonar just sounds better, don't you think? It really rolls off the tongue.

Sonar, just like

• spider silk
• gecko grip
• leopard print

has been around in nature for a long time. It wasn't until World War I that we managed to actually create a manmade system for detecting objects using sound. It all started with Isaac Newton and his wave equation. Although it was controversial at the time (like most big ideas), Newton firmly believed that sound was a wave. In his downtime between figuring out that sound and wave business, he also happened to build a mathematical foundation for physics, NBD.

The first man to experiment with how sound could be used for navigation and ranging did so by sticking a music bell underwater. Literally. Originally a lawyer, Jean-Daniel Colladon found that he really liked setting up experiments a whole lot more than practicing law. It was probably because those wigs and robes just didn't sit right on him.

Either that or Colladon really cared about helping people with science. In fact, he decided to test his first sonar-like object after the Titanic sank into the sea. Both he and Lewis Nixon became independently obsessed with finding a way to detect icebergs. In 1906, Nixon patented a method to find those sneaky icebergs.

Kate and Leo would be so proud.

Nixon's machine might have spelled the end for iceberg-related sinkings, but it didn't actually use echolocation. That technology didn't come until Paul Langévin invented it in 1914. Once it was figured out, the invention opened the door for modern sonars to be developed and improved. Our personal favorite was the work of Dr. Robert H. Rines, who devoted his life to finding the Loch Ness monster using sonar technology. (Source)