Before building a structure you must first consider your situation. Your shelter should be able to protect you from heat, wind, rain, sun, snow, and any weather that is around you. Shelter is mainly for protection and comfort,protection from weather and also animals or bugs. It should be relatively comfortable because you must be able to sleep, for that is a basic human need.
A shelter can range from a “natural shelter”; such as a cave or a fallen-down (cracked but not split) thickly-foliaged tree, to an intermediate form of man-made shelter such as a debris shelter, a ditch dug next to a tree log and covered with foliage, or a snow cave, to completely man-made structures such as a tarp, tent, or house.
Making fire is recognized in the sources as to significantly increase the ability to survive physically and mentally. Lighting a fire without a lighter or matches, such as by using natural flint and steel with tinder, is a frequent subject of both books on survival and in survival courses. There is an emphasis placed on practicing fire-making skills before venturing into the wilderness.
Fire is presented as a tool meeting many survival needs. The heat provided by a fire warms the body, dries wet clothes, disinfects water, and cooks food. Not to be overlooked is the psychological boost and the sense of safety and protection it gives. In the wild, fire can provide a sensation of home, a focal point, in addition to being an essential energy source. Fire may deter wild animals from interfering with the survivor, however wild animals may be attracted to the light and heat of a fire. The light and smoke emitted by a fire can also be used to work at night and can signal rescue units.
A human being can survive an average of three to five days without the intake of water, assuming sea-level altitude, room temperature and favorable relative humidity. In colder or warmer temperatures, the need for water is greater. The need for water also increases with exercise.
A typical person will lose minimally two to maximally four liters of water per day under ordinary conditions, and more in hot, dry, or cold weather. Four to six liters of water or other liquids are generally required each day in the wilderness to avoid dehydration and to keep the body functioning properly. The U.S. Army survival manual recommends that you drink water whenever thirsty.  Other groups recommend rationing water through “water discipline”.
A lack of water causes dehydration, which may result in lethargy, headaches, dizziness, confusion, and eventually death. Even mild dehydration reduces endurance and impairs concentration, which is dangerous in a survival situation where clear thinking is essential. Dark yellow or brown urine is a diagnostic indicator of dehydration. To avoid dehydration, a high priority is typically assigned to locating a supply of drinking water and making provision to render that water as safe as possible.
Many sources in survival literature, as well as forums and online references, list ways in which water may be gathered and rendered safer for consumption in a survival situation, such as boiling, filtering, chemicals, solar radiation / heating (SODIS), and distillation (regular or via solar distillation). Such sources also often list the dangers, such as pollutants, microorganisms, or pathogens which affect the safety of back country water.
The issues presented by the need for water dictate that unnecessary water loss by perspiration be avoided in survival situations.
To thus avoid these problems, culinary root tubers, fruit, edible mushrooms, edible nuts, edible beans, edible cereals or edible leaves, edible moss, edible cacti and algae can be searched and if needed, prepared (mostly by boiling). With the exception of leaves, these foods are relatively high in calories, providing some energy to the body. Plants are some of the easiest food sources to find in the jungle, forest or desert because they’re stationary and can thus be had without exerting much effort.
Some survival books promote the “Universal Edibility Test”. Allegedly, one can distinguish edible foods from toxic ones by a series of progressive exposures to skin and mouth prior to ingestion, with waiting periods and checks for symptoms. However, many other experts including Ray Mears and John Kallas reject this method, stating that even a small amount of some “potential foods” can cause physical discomfort, illness, or death. An additional step called the scratch test is sometimes included to evaluate the edibility of a potential food.
Focusing on survival until rescued by presumed searchers, The Boy Scouts of America especially discourages foraging for wild foods on the grounds that the knowledge and skills needed are unlikely to be possessed by those finding themselves in a wilderness survival situation, making the risks (including use of energy) outweigh the benefits. Given that most people have enough body fat to carry them through several days, using the energy to procure water, fire and shelter is a better use of available time and energy.
First aid (wilderness first aid in particular) can help a person survive and function with injuries and illnesses that would otherwise kill or incapacitate him/her. Common and dangerous injuries include:
- Lacerations, which may become infected
- Bites or stings from venomous animals, such as: snakes, scorpions, spiders, bees, stingrays, jellyfish, catfish, stargazers, etc.
- Bites leading to disease/septicemia, such as: mosquitoes, fleas, ticks, animals infected with rabies, sand flies, komodo dragons, crocodilians, etc.
- Infection through food, animal contact, or drinking non-potable water
- Bone fractures
- Sprains, particularly of the ankle
- Poisoning from consumption of, or contact with, poisonous plants or poisonous fungi.
- Hypothermia (too cold) and hyperthermia (too hot)
- Heart attack
The survivor may need to apply the contents of a first aid kit or, if possessing the required knowledge, naturally-occurring medicinal plants, immobilize injured limbs, or even transport incapacitated comrades.
These two pictures of the same tree trunk in the Northern Hemisphere are an example of a navigational terrain feature. The left picture shows the northern side of a trunk, where darker and more humid micro climatic conditions favor moss growth. The right picture is south, with sunnier and drier conditions, less favorable for moss growth. The shady side is not always opposite the noon side.
Survival situations are sometimes resolved by finding one’s way to safety, or one may need to move to find a more suitable location to wait for rescue. The sources observe that to do either of these safely requires some navigation equipment and skills. Types of navigation include:
- Celestial navigation, using the sun and the night sky to locate the cardinal directions and to maintain course of travel
- Using a map and compass together, particularly a topographic map or trail map.
- “Navigation by observation” of terrain features on a map or otherwise known
- Using a GPS receiver, if one is available
- Dead reckoning
In the Northern Hemisphere at midday, the sun is directly South of any observer. In the Southern Hemisphere at mid-day, the sun is directly North of any observer. Mid-day can be calculated by planting a stick or other upright structure in the ground as close to 90 degrees as possible and marking with sticks or rocks or any other feature, as often as possible, the length of the shadow it casts during a single daylight period. Wherever the shadow is the shortest during a daylight period, that direction is South if you are in the Northern Hemisphere, or North if you are in the Southern Hemisphere. In lieu of a compass or natural terrain features to aid in navigation, this method will give a survivor a generally correct impression of direction. This method of orienteering is not useful when the survivor does not have a pre-existing general impression of the local environment (knowing which way is south will not help you if you don’t know what should be south of you).
Survival training has many components, mental competence and physical fitness being two. Mental competence includes the skills listed in this article, as well as the ability to admit the existence of a crisis, overcome panic, and think clearly. Physical fitness includes, among other abilities, carrying loads over long distances on rough terrain. Theoretical knowledge of survival skills is useful only if it can be applied effectively in the wilderness. Almost all Survival Skills are environment specific and require training in a particular environment.
Survival training may be broken down into three types, or schools; Modern Wilderness Survival, Bushcraft, and Primitive Survival Techniques.
Modern Wilderness Survival teaches the skills needed to survive Short-Term (1 to 4 Days) and Medium-Term (4 to 40 Days) survival situations.
“Bushcraft” is the combination of Modern Wilderness Survival and useful Primitive Survival Techniques. It normally splits its skill acquisition between Medium-Term Survival Techniques (4 to 40 Days) and Long-Term Survival Techniques (40 Days Plus).
Primitive Survival Techniques or “Primitive Living” teaches the skills needed to survive over the Long-Term (40 days plus). Many primitive technology skills require much more practice and may be more environment specific.
Several organizations offer wilderness survival training. Course ranges from one day to field courses lasting as long as a month. In addition to teaching survival techniques for conditions of limited food, water, and shelter, many organizations that teach bushcraft and Primitive Survival seek to engender appreciation and understanding of the lifestyles of pre-industrialized cultures.
There are several books that teach one how to survive in dangerous situations, and schools train children what to do in the event of an earthquake or fire. Some cities also have contingency plans in case of a major disaster, such as hurricanes or tornadoes.
Different training is necessary to survive in different climates. Although one technique may work in a dry sub-Saharan area, the same methods may actually be a detriment to health in an arctic climate.
Commentators note that the mind and its processes are critical to survival. It is said that the will to live in a life and death situation often separates those that live and those that do not. Stories of heroic feats of survival by regular people with little or no training but a strong will to live are not uncommon. Laurence Gonzales in his book Deep Survival: Who Lives, Who Dies and Why describes the story of a young teenage girl named Juliane Köpcke who is the victim of a plane crash in the Amazon jungle. With no formal training and wearing only her confirmation clothes, she walked through the jungle for several days with parasitic insects boring under her skin. After eleven days, with very little food, she reached a hut and collapsed inside. Three hunters found her the next day and took her to a local doctor. Of those who survived the crash, she was the only one to make it out alive. Gonzales believes that her simple and indestructible will to live made the difference.
So stressful is a true survival situation, that those who appear to have a clear understanding of the stressors, even trained experts, are said to be mentally affected by facing deadly peril.
It seems that, to the extent that stress results from testing human limits, the benefits of learning to function under stress and determining those limits may outweigh the downside of stress. After all, stress is a natural reaction to adverse circumstances, developed by evolution to assist in survival – at least, in terms of brief, perilous encounters (such as being caught in the middle of a natural disaster, or being attacked by a wild animal.) If stress lingers for a prolonged period of time, it tends to produce the opposite effect, impeding one’s ability to survive. In particular, the commentators note the following adverse effects of stress: forgetfulness, inability to sleep, increased propensity to make mistakes, lessened energy, outbursts of rage, and carelessness. None of these symptoms would seem to make survival easier or more likely.
There are certain strategies and mental tools that can help people cope better in a survival situation, including focusing on manageable tasks, having a Plan B available and recognizing denial.