Almost of swimmers consider temperatures of thirty degrees or more to be excessively warm for comfortable swimming. Triathletes utilize a standard measurement of 24 degrees Celsius (75 degrees Fahrenheit) as the temperature limit for wearing wetsuits. The highest limit of cold water according to the regulation is 24 degrees. However, athletes often participate in events where the temperature of the water is well below 24 degrees. The main danger from cold waters is hypothermia. This can be avoided by staying with the group and never trying to outrun the chill. Get into the habit of doing some sort of aerobic activity when in the water because this will help your body produce heat faster. Even at 24 degrees, you should avoid diving if possible because the pressure changes that occur when you go under the surface can lead to brain damage. Swimming in cold waters isn't dangerous as long as you don't get chilled first. The main thing is to stay with the group and never try to outrun the chill. If you feel dizzy or uncoordinated, get out of the water immediately so you don't hurt yourself.