Marine geology is the scientific study of the Earth's ocean floors, coastal environments, and submarine geological processes, encompassing seafloor morphology, sediment distribution, tectonic activity, and underwater volcanic systems. Within GIS workflows, marine geology leverages advanced spatial analysis techniques to integrate multibeam bathymetric data, seismic reflection surveys, sediment core records, and oceanographic datasets into unified geospatial data frameworks. GIS technology enables geospatial analysts to visualize three-dimensional seafloor terrain, map fault lines and sedimentary basins, and model hydrocarbon reservoir extents with high spatial precision. Raster-based terrain analysis, vector digitization of geological boundaries, and geostatistical interpolation are commonly applied methods that transform raw marine survey data into actionable geospatial intelligence. Practical applications include offshore energy exploration, submarine cable route planning, tsunami hazard assessment, marine protected area delineation, and coastal erosion monitoring. By consolidating diverse geospatial data sources into interactive mapping platforms, GIS professionals can support evidence-based decision-making for environmental management agencies, offshore engineering firms, and government regulatory bodies operating in marine and coastal domains.