Just two and a half hours per week of aerobic physical activity — such as swimming — can decrease the risk of chronic illnesses. It can also lead to improved health for people with diabetes and heart disease. Swimmers have about half the risk of death at a given age compared with inactive people of the same age. People report enjoying water-based exercise more than exercising on land. They can also exercise longer in water than on land without increased effort or joint or muscle pain. Water-based exercise can help people with chronic diseases. For people with arthritis, it improves the use of affected joints without worsening symptoms. People with rheumatoid arthritis have more health improvements after participating in hydrotherapy than with other activities. Water-based exercise also improves the use of affected joints and decreases pain from osteoarthritis. Water-based exercise improves mental health, as well. Swimming can improve mood in both men and women. For people with fibromyalgia, exercise therapy in warm water can decrease depression and improve mood. Water-based exercise can improve the health of mothers and their unborn children and has a positive effect on the mothers’ mental health. Parents of children with developmental disabilities find that recreational activities such as swimming improve family connections. Water-based exercise can benefit older adults by improving the quality of life and decreasing disability. It also improves or maintains the bone health of post-menopausal women. Ready to start your own personal swimming program? Join a water-aerobics class? Or learn to swim if you don’t already know how? Get your doctor’s OK, then dive in! The water’s fine.