The chapter “Basic Notions of Navigation and Maneuvering at Sea” provides a comprehensive overview of the essential principles of maritime navigation and their critical role in offshore oil production operations. It begins by classifying navigation into oceanic, coastal, and restricted waters, outlining their specific precision requirements and position-fixing frequencies. The text then explores the types of navigation techniques—celestial, visual, electronic, and dead reckoning—highlighting how they ensure safe vessel movement in various marine environments. A detailed explanation of the Earth’s geometry, including great and small circles, geographic coordinates, and map projections (especially the Mercator projection), establishes the foundation for chart-based navigation. The chapter also defines bearings (true, magnetic, and compass) and explains how magnetic declination and deviation affect course plotting. It introduces the units of measurement used in navigation, such as nautical miles, knots, and angular degrees, and describes a wide range of navigational instruments, from traditional compasses and sextants to modern GPS and ECDIS systems. Additionally, it summarizes the International Regulations for Preventing Collisions at Sea (COLREGs) and their role in ensuring maritime safety through standardized vessel behavior, lights, and signals. Finally, the chapter connects navigation fundamentals to offshore oil operations, emphasizing their application in oil offloading, water and diesel transfers, cargo movements, diving activities, and simultaneous offshore operations. It stresses the importance of dynamic positioning, drift control, environmental monitoring, communication, and regulatory compliance to ensure safety, efficiency, and environmental protection in complex offshore environments.