We use reflected light to see. But some animals do that with sound. They emit high-pitched sounds and listen to the echoes to create a mental image of their surroundings. The pioneers of this strategy are bats and whales. The strategy is called echolocation. Did you know that even humans can echolocate. How does it work? How have scientists attempted to apply biological sonar to create various technologies such as smart canes, self-driving cars, autonomous underwater vehicles (AUVs), remotely operated underwater vehicles (ROVs), sonar-sense drones and bacteria? Explore the module to learn more.