Environmental information is important for successful planning and execution of naval operations. A thorough understanding of environmental variability greatly increases the likelihood of mission success. To ensure that naval forces have the most up-to-date capabilities, the Office of Naval Research (ONR) has an extensive environmental research program. This research, to be of greatest use to the warfighter, needs to be directed towards assisting and solving battlefield problems. To increase research community understanding of the operational demands placed on naval operators and to facilitate discussion between these two groups, the National Research Council's (NRC) Ocean Studies Board (OSB), working with ONR and the Office of the Oceanographer of the Navy, convened five previous symposia on tactical oceanography. Oceanography and Mine Warfare examines the following issues: (1) how environmental data are used in current mine warfare doctrine, (2) current procedures for in situ collection of data, (3) the present capabilities of the Navy's oceanographic community to provide supporting information for mine warfare operations, and (4) the ability of oceanographic research and technology developments to enhance current mine warfare capabilities. This report primarily concentrates on the importance of oceanographic data for mine countermeasures.