I will summarize recent work on the applications of Lagrangian techniques to characterize transport and mixing in the marine surface. Velocity field data are obtained from realistic simulations and from satellite altimetry of the surface layers of the sea surface. I will compare the ability of Lagrangian methods and standard Eulerian diagnostics in locating instantaneaous coherent structures and in the analysis of climatological transport and mixing properties. Some applications to biological processes in the marine environment (like coastal upwelling areas) will be also discussed.