The flux of atmospheric water vapor has been examined as part of a more extensive study on general circulation and energetics in the area of the Central American seas. The analysis is based on twice daily radiosonde data for the entire year 1960. During the winter half of the year, a westward directed moisture transport is concentrated in a relatively narrow band over the southern Caribbean Sea. The flux of water vapor over the Gulf of Mexico is directed roughly eastward. An increase of the transport downstream indicates the excess of evaporation over precipitation. In summer, a strong moisture flux extends from the Caribbean Sea over the Gulf of Mexico into the interior of the North American continent. The water vapor transport decreases downstream, which means an excess of precipitation over evaporation. The eddy moisture flux and flux divergence over the Gulf of Mexico reaches considerable proportions in winter, while it is comparatively small over the Caribbean Sea throughout the year. The water vapor flux divergence is discussed with regard to estimates of lane-scale precipitation and independent computations of the sensible and latent heat flux at the sea-air interface.