3 minutes without breathing (asphyxiation, blood loss) 3 hours without shelter in an extreme environment (exposure) 3 days without water (dehydration) 3 weeks without food (starvation). The rule of 3-3-3 is not set in stone, but rather a guideline to give you the best chance of survival.
There are certainly people who can hold their breath longer than 3 minutes. But, on average, after that time has expired you are entering some pretty dangerous territory. Lack of oxygen can cause a multitude of issues especially when you are in a survival situation and your body is already stressed. Even altitude sickness where the air is thin and less oxygen is present can pose serious health risks.
Extreme environments like excessive heat or cold can also be deadly. Exposure is something that can quickly kill you. Wet clothes and a cold environment can easily lead to hypothermia and eventually death. Being stuck in an oppressively hot environment can be just as dangerous. No shade, not enough water, over exertion are all a potentially deadly combination.
Water and food are the last parameters that need attention. Water being the most important of the two. Going 3 days without water and you’re in trouble. Physical and cognitive ability begin to drastically decline and critical decision making skills evaporate. Make sure that you have some basics covered regardless of the difficulty level of your next outing. Better safe than sorry.
