The favorable outcome of an autonomous existence depends on many reasons: physical and psychological condition, food and water supplies, equipment efficiency, etc.

The Arctic and the tropics, mountains and deserts, taiga and the ocean  each of these natural zones is characterized by its own characteristics, which determine the specifics of human life (rules of behavior, methods of obtaining water and food, construction of a shelter, the nature of diseases and measures to prevent them, methods of movement around the terrain).

The more severe the conditions of the external environment, the shorter the periods of autonomous existence, the more stress the struggle with nature requires, the stricter the rules of behavior must be followed, the more expensive is the price with which each mistake is paid.

A person's vital activity is greatly influenced by his will, determination, concentration, ingenuity, physical fitness, endurance. But even these important qualities are sometimes not enough for salvation. People die of heat and thirst, not suspecting that there is a saving source of water three steps away, they freeze in the tundra, unable to build a shelter from snow, die of hunger in the forest, where there is a lot of game, become victims of poisonous animals, not knowing how to provide first aid for a bite.

When a person is in any type of terrain, the chances of survival depend on the following factors: 

• desire to survive; 
• the ability to apply existing knowledge, strictly comply with the requirements of stay in a particular area; 
• confidence in the knowledge of the area; 
• prudence and initiative;  discipline and ability to act according to plan; 
• the ability to analyze and take into account their mistakes.

To survive means to solve three critical tasks:

1. To be able to take shelter from cold, heat and wind, to protect the body from hypothermia or overheating, depending on the terrain and weather conditions.

2. Immediately set the daily rate of water consumption, and leave an emergency supply as a last resort. Steps must also be taken to locate water sources.

3. Make a diet and make sure there is enough water for cooking and eating.

(based on materials of «Энциклопедии безопасности» Громова В.И. и Васильева Г.А., Москва. 1998)