Freshwater diving
Freshwater diving is the practice of scuba diving in freshwater systems. It usually completed in a freshwater lake, but often in a river, cave, or even a flooded quarry. Despite being a potentially dangerous activity it can be rewarded with interesting aquatic life and even in some areas extremely high visibility, which can often be found in caves.
Hazards
This type of scuba diving is not seen as an advanced method, but has some specific hazards associated with the location and characteristics of freshwater systems, including altitude, extreme temperature, and visibility.
Temperature
Freshwater divers are often challenged by the cold water and are at a high risk of developing hypothermia.
Water temperatures in lakes often vary (lakes in the stratification zone have a general seasonal pattern) due to seasonal changes in lake stratification, hence affecting the temperature. The water can often reach below 4.5°C out of summer and in most winters will freeze over in temperate parts of the world. The diver is at a high risk of hypothermia or frostbite. A dry suit or semi-dry suit must be worn to attempt to prevent this.
Altitude
Ice diving is often conducted in mountain lakes at altitude. Altitude diving techniques such as decompression practice are vital at elevations over 300 meters, because of the greater risk of decompression sickness.