The interaction between multiple scales in nature and mainly in turbulent flows produces fractals or multifractal structures. We use multi-fractal analysis to investigate the scales and influence of stratification in different types of surface eddies in the ocean, and specially, near the coastline. We will also show and discuss the structure and residence time in oil spills and slicks in the ocean surface. This method, of multifractal analysis on the intensity SAR signals, as an example will also be applied to experiments of unstable mixing fronts driven by Rayleigh-Taylor Instabilities. These hydrodynamic instabilities are a fundamental buoyancy or acceleration driven mixing process since they are the main causes of mixing and regulate for example the overturning process. A turbulent model is used in order to study the self-similar mixing process. The results are parameterized in terms of the Atwood number, which in terms of initial condition evaluation seems more convenient than using reduced gravity or buoyancy flux. The advance of the mixing front can be compared to several laboratory and field measurements, showing the effects of the initial perturbations and the two-dimensionality and boundary conditions of a model that combines 3 and 2 dimensional effects. The multi-fractal analysis reflects the flow conditions and allows us to understand further the mixing processes.