Did you know that the technology used by submarines is called 'echolocation' or SONAR? The submarine emits sound waves that reflect on objects in the environment. We have learned this principle from animals such as dolphins and bats.
Bats are able to navigate very well, because they store the results from their echolocation in 'mind maps'. By doing so, they are able to build a map of their environment. SONAR Light Pulse mimics this technique, but uses a light wave. Want to know if there is someone on the other side of the tunnel? Just send a light wave by calling out.