Single-beam sonar is a technology used to measure the depth of water and map underwater features. It works by sending out a single sound wave pulse from a transducer, which travels through the water, hits the seabed, and then returns to the transducer. The time it takes for the sound wave to return is used to calculate the depth. This method is commonly used in marine surveys, fishing, and navigation. Single-beam sonar is simpler and less expensive than multi-beam sonar systems, making it a popular choice for smaller vessels and projects that require basic depth information.