This paper presents a unified theory on the interrelationship between electrochemical and mechanical factors causing damage to materials subjected to cavitating environments. The ambiguous term “cavitation erosion” is rejected in favor of three modes of damage which depend on the severity of cavitation collapse forces: Cavitation Deformation or Fracture; Cavitation Fatigue; and Cavitation Corrosion. The authors describe some model propeller experiments which demonstrate Cavitation Fatigue damage and how specific cathodic protection measures reduce the damage. An extensive bibliography is appended. 3.5.3