Subsurface temperature data collected from research vessels and aircraft and vessels of opportunity are used to describe the evolution of the major El Ni¿o event in the tropical Pacific from September 1982 through September 1983. Optimum interpolation is used to create size analysis maps of the anomalous depths of the 20¿C, 15¿C, and 10¿C isothermal surfaces. The region analyzed is 20¿N to 20¿S and 140¿W to the coast of the Americas. Each analysis is based on data accumulated over about a month, and the analysis periods are separated by about a month. The depths of the 20¿C isotherm are used to compute zonal thermoclinic transports across 100¿W of the North and South Equatorial currents and the North Equatorial Countercurrent. ¿ American Geophysical Union 1989