The document discusses the physical properties and physiological effects of hydrotherapy. It describes how water exhibits laminar and turbulent flow patterns affected by factors like drag. Immersion in water can impact cardiovascular functions like heart rate and blood pressure through mechanisms like the dive reflex. Hydrotherapy can also influence other body systems including respiratory, renal, neurological, and muscular systems. The mechanical effects of water like debridement are discussed. Benefits of aquatic therapy include improved balance, strength, flexibility and mobility. Therapeutic effects involve pain relief, relaxation, and range of motion. Clinical contraindications are also noted.