Survival skills
A human being can survive an average of three to five days without the intake of water. The issues presented by the need for water dictate that unnecessary water loss by perspiration be avoided in survival situations. The need for water increases with exercise.
Tardigrade
Tardigrades are considered to be able to survive even complete global mass extinction events due to astrophysical events, such as gamma-ray bursts, or large meteorite impacts. Some of them can withstand extremely cold temperatures down to (close to absolute zero), while others can withstand extremely hot temperatures up to for several minutes, pressures about six times greater than those found in the deepest ocean trenches, ionizing radiation at doses hundreds of times higher than the lethal dose for a human, and the vacuum of outer space. They can go without food or water for more than 30 years, drying out to the point where they are 3% or less water, only to rehydrate, forage, and reproduce. Tardigrades that live in harsh conditions undergo an annual process of cyclomorphosis, allowing for survival in sub-zero temperatures.