The seismic data analysis (SDA) software system facilitates generation of marine seismic reflector databases composed of reflector depths, travel times, root-mean-square and interval velocities, geographic coordinates, and identifying information. System processes include digitizing of seismic profiles and velocity semblance curves, merging of velocity and navigation data with profile travel-time data, calculation of reflector depths in meters, profile and map graphic displays, data editing and smoothing, and entry of finalized data into a comprehensive database. An overview of concepts, file structures, and programs is presented.