The fins’ structure places the foot pocket at medium height from the blade to make efficient the strength transmission, with a progressive and pleasant fluttering for the swimmer. However, it reduces the hydrodynamic resistance of the high part of the foot pocket. The sole has rigidity calculated to avoid cramps in that area. The back part of the foot pocket is thicker; it has reinforcement and a flap that facilitates the insertion. All the profiles that are in contact with the skin are round, for greater comfort. LIGHT combines three different materials in its structure: Polypropylene for the blade and the sole area. This material highlights because of its great lightness and resistance to salt water, chlorine and ozone. It’s unalterable with the pass of time and it maintains its features due to its great resistance. It’s completely unbreakable, both by tension or torsion in any sense. Round reinforcement elastomer in the low profile of the blade. It avoids wear by erosion and protects other swimmers from occasional impacts. Very soft and comfortable elastomer (thermoplastic rubber). It’s applied in the high part of the foot pocket and the side nerves of stabilization of the fins during swimming. The proportions of the mold base Cressi-sub are highlighted, which it is evolving constant to adapt to the morphologic variations that the habits of footwear have provoked in the average proportions of the European foot (almost 20 % in the last 30 years) For the placed trades on line of coast, the option of a short fin of great resistance is also specially interesting as help to the displacement and protection for snorkeling light, specially in rocky zones.