"hippo" Hydro-Pneumatic Fenders are best employed for submarines. One of the most important criteria for using Hydro-Pneumatic Fenders is high energy absorption capacity and low reaction force, a vital factor for submarine applications. The Hydro-Pneumatic Fender provides a better contact area vertically which cannot be achieved through any other fendering systems and hence makes the Hydro-Pneumatic Fender the most ideal for submarine use.