The path integral technique is applied to investigate the effects of internal waves and temperature fine structure on multipath propagation in the ocean. The novel feature of this study is the use of ray tracing to evaluate the stationary paths between source and receiver. An expression for the correlation of the acoustic pressure propagated along disjoint paths is derived which describes both deterministic and random effects. Numerical results are obtained for the interference of two rays in the presence of a bilinear sound‐speed profile. These results clearly demonstrate that internal waves rather than oceanic fine structure govern the decorrelation of acoustic energy propagated along the two paths.