They also reduce vibrations caused by moving the fins underwater.
HYDRO fins have rubberised side reinforcements, increasing the elasticity of the feathers, prolonging the life and affecting the stability of the fins. To improve performance, the HYDRO fin feathers are inclined at a 20-degree angle to the calliope. In order to minimise the load exerted on the diver's feet, the soles of the HYDRO fins are suitably reinforced and the presence of holes in the front of the wellingtons means that sand and stones do not irritate the feet and can flow freely, along with the water, out of the wellingtons.