70 degrees Fahrenheit"High aerobic activity in high temperature water can be dangerous," according to the United States Water Fitness Association. Conversely, swimming in temperatures below 70 degrees Fahrenheit can lead to increased heart rate and blood pressure.
Can you get hypothermia in 68 degree water?
This condition can be caused by prolonged exposure to temperatures below 10°C (50°F), or by prolonged immersion in cold water below 20°C (68°F). If left untreated, hypothermia can eventually lead to complete heart and respiratory failure and ultimately death.