The Salvinia effect describes the permanent stabilization of an air layer upon a hierarchically structured surface submerged in water. Based on biological models (e.g. the floating ferns Salvinia, backswimmer Notonecta), biomimetic Salvinia-surfaces are used as drag reducing coatings (up to 30% reduction were previously measured on the first prototypes. When applied to a ship hull, the coating would allow the boat to float on an air-layer, reducing energy consumption and emissions. Such surfaces require an extremely water repellent super-hydrophobic surface and an elastic hairy structure in the millimeter range to entrap air while submerged. The Salvinia effect was discovered by the biologist and botanist Wilhelm Barthlott (University of Bonn) and his colleagues and has been investigated on several plants and animals since 2002. Publications and patents were published between 2006 and 2016. The best biological models are the floating ferns (Salvinia) with highly sophisticated hierarchically structured hairy surfaces, and the back swimmers (e.g.Notonecta) with a complex double structure of hairs (setae) and microvilli (microtrichia). Three of the ten known Salvinia species show a paradoxical chemical heterogeneity: hydrophilic hair tips, in addition to the super-hydrophobic plant surface, further stabilizing the air layer.