Fan bodies in the North Falkland Basin, including those that comprise the reservoir in the Sea Lion Field, have been defined seismically with the aid of several seismic attributes. This has provided a greater understanding of their geomorphology, potential reservoir variations and distribution, and has helped illuminate the full extent of some fans as well as the internal architectural detail of others. The attributes used include reflectivity attributes on full-stack and part-stack three-dimensional (3D) seismic data, impedance attributes on inverted seismic data, isochron attributes, and geometric attributes such as coherence, dip, curvature and spectral decomposition. The combination of spectral decomposition and high-resolution visualization techniques has greatly aided the identification and interpretation of some of the fans. Colour blending, where separate colours relating to different frequency ranges are blended into a single image, can reveal additional detail within the fan systems. Specific colour blends are seen to highlight separate sand bodies, as well as thickness variations, and have helped to resolve stratigraphic and petrophysical heterogeneity. Seismic attribute responses have been quantified with the integration of well data from the 18 wells within the 3D data set. This has resulted in a detailed reservoir characterization and definition of geological features within some of the fan bodies. This detailed use of seismic attributes on the North Falkland Basin 3D data set has been of benefit for both the appraisal and development of the Sea Lion Field, and has also helped to define future exploration targets and well locations within the basin.