Inhomogeneity is a characteristic of every real medium, and two types are observed, regular and random. Regular inhomogeneities are produced by spatial variation of the mean characteristics of a medium, for example, velocity variation with temperature, depth and salinity. Random inhomogeneities are produced by deviation from the mean values. In the paper a medium with random inhomogeneities is modelled and ray diagrams illustrate the effect of the magnitude and scale size of the inhomogeneities on the propagation of sound. The sound speed of the medium varies with both range and depth and thus may be described by correlation lengths in both dimensions. The results' presented relate to an existing extreme experimental situation where the propagation range is 170 m with horizontal correlation length of 20 m, vertical correlation length 2 m, and a standard deviation of the local sound speed from the local mean of 0.5 m/s. The modelling results are compared with experimental results.