The acoustic propagation losses between a 230‐Hz cw source and a multi‐hydrophone receiving system were measured over Dickins Seamount in the Northeast Pacific. The source was towed at depths of 18 and 184 m. The receiving system had hydrophones spaced in depth from 323 to 633 m. The measurements were made to a maximum range of 130 km with the receiver located at a range of 60 km from the seamount peak. The results show that the seamount cast an acoustic shadow over the receiver, increasing the propagation loss by up to 15 dB, when the source was shallow and in a position which enabled the seamount to intercept all of the deep refracted source energy. Back reflections from the seamount with levels 6 to 13 dB below the direct signal level were present when the shallow source was 3 to 5 km from the seamount peak. Downslope reflections enhanced the direct signal by up to 10 dB when the shallow source was within 3 km of the peak. Acoustic shadowing and reflection effects were minimal in the results for the deep source because most of the source energy propagated along the sound‐channel axis above the seamount peak. The analysis indicates that ray theory is adequate for describing the reflection effects of the acoustic propagation but does not account for all of the acoustic energy in the shadow zone.