The objectives of this research project include the reprocessing of a high-quality 3-D multichannel seismic (MCS) reflection data set collected across the Costa Rica margin accretionary prism, and subsequent reinterpretation of the prism's structure, geomorphology, and geohydrology. Advances in MCS data processing techniques, and increasing interest in the internal structure of accretionary prisms make this project of timely importance. In addition to answering fundamental questions concerning the nature of structures within the Costa Rica accretionary prism, the reprocessed seismic data will be used as background information for future Ocean Drilling Project activities in the Costa Rica margin area.