A wave energy converter (WEC) which is called Anaconda, is a cost effective wave energy device. The device seeks to exploit the concept of a distensible rubber tube. The concept of Anaconda has been proven at small laboratory scale and is seen as having low capital and operational costs. Different rubbers were quantified for building a good understanding of the range of stress-strain behavior and fatigue of rubber. The magnitude of the softening of several rubber formulations depends on the maximum strain applied. The larger the maximum strain applied, the greater the softening. A versatile tensile fatigue test machine was developed to enable a better understanding of fatigue, including non-relaxing fatigue to be developed for rubber or any other materials. For the fixed strain conditions used to screen candidate rubbers, a specific rubber compound performed the best compared both to the same unfilled rubber with antioxidant or no antioxidant in place, and a wide range of filled rubbers. The estimation on dynamic stress-strain loops and cyclic stress relaxation rates of each rubber has been made.