This module provides a comprehensive introduction to the theory and practical use of side-scan sonar systems in hydrographic surveying. Participants learn how side-scan sonar works, how to plan and execute surveys, and how to install, calibrate, and operate sonar equipment effectively. The course covers underwater acoustics and sound velocity fundamentals, as well as techniques for optimizing towfish performance. Real-world examples and sonar imagery help participants develop the skills to recognize seabed features and interpret side-scan sonar data accurately.