Shallow‐water attenuation loss was studied under varying oceanographic conditions within a standard area. By using combined ship‐aircraft measurement methods, sound‐propagation characteristics were ascertained in conjunction with relevant environmental parameters. The selected sea area had only very slight lateral variation for all environmental characteristics permitting good control of measurements. Evaluations to date indicate typical frequency‐response differences for attenuation, with or without sea‐surface participation in sound propagation. With bottom participation only, the magnitude and frequency response of the attenuation have a first approximation consisting of a model with the bottom represented only as a quasiliquid smooth stratification of the complex sound velocity and density.