Transmission loss as a sonar parameter describes the magnitude of acoustic energy loss of sound propagation in the ocean. Broadband (10 Hz – 300 kHz) propagation loss measurements conducted over the years in varying areas show the effect of the spatial and temporal variability on acoustic propagation for bottom-limited conditions. An example from the existing acoustic data obtained over the last three decades has been utilized to demonstrate the effects of environmental variability on propagation loss, and our ability to simulate the propagation conditions with existing propagation models are presented.