3-D prestack depth migration is quickly coming of age. New plays beneath salt-injection features have received much recent attention. However, accurately defining reservoir geometries in more mature areas, such as the North Sea or the Gulf of Suez, also requires 3-D depth imaging technologies. Although 3-D depth imaging is a field of active development, basic elements such as velocity definition and the migration algorithm itself are developed enough to discuss their applications on a field data set.