Rapid advances in the understanding of fundamental geologic processes have been achieved, in part, through the use of marine multichannel seismic (MCS) reflection techniques over the past decade. Academic MCS studies have provided new insights into the formation and evolution of the oceanic lithosphere by revealing, in a few places, magma chambers under oceanic spreading centers and by documenting major crustal thinning under fracture zones in the western Atlantic. At rifted continental margins, MCS data have greatly advanced studies of the deep structure and evolution of sedimentary basins and the development of sedimentary sequences and their relation to paleoenvironments and eustatic sea level changes. At convergent margins, MCS data have provided critical information on the development of modern for‐earcs and accretionary wedges that are the submarine analogues of the fold and thrust belts of ancient orogenic belts.