The concept of scale (in sensu lato) is considered to be very promising as the integrative basis for modern ecology. Nowadays it is not a full-blown theory but rather a flexible and progressively developing methodology to outline future unifying theories. It provides a powerful conceptual framework for generating testable hypotheses and studying a wide range of ecological phenomena related with such themes as heterogeneity, hierarchy and size. Spatio-temporal heterogeneity, organizational hierarchies and body size are the main scaling factors for ecological patterns and processes. Broad comparison of patterns for these three different but interrelated dimensions can reveal some new regularities ("scaling laws") of ecological systems. It also allows us to look at the worlds of different organisms "through their own eyes". Some examples of applying the cross-scaling approach in marine ecology are considered: — Patterns and scales of spatial heterogeneity; — Species-area curves and body size; — Co-occurrence of congeners as scale-dependent phenomenon; — Spatio-temporal ranges of ecological hierarchies.