Computation of propagation losses are presented for 200‐ to 2000‐cps sound in 25‐fathom water to ranges of 250 miles over different bottoms for a zero gradient (isospeed), and out to 50 miles for a both weak negative gradient and a strong negative gradient. The ray method is used, together with the assumption of random phase after the first bottom reflection, to formulate the theory. The resulting computed transmission loss anomalies exhibit a marked dependence on: (1) the ratio of source depth to wavelength, (2) the sound‐speed gradients, and (3) bottom reflection losses at small grazing angles. The bottom reflection losses are strongly dependent on the attenuation in the bottom. Some long‐range experimental data are presented which show a quantitative agreement with the computed curves out to ranges of 40 miles.