Hiking equipment
According to Tom Brown, the basic plan for survival is in the order of shelter (including clothing), water, fire, and food. Cody Lundin writes about the "Rule of 3s"; this relates to human survival without basics: three minutes without air, three hours without shelter, three days without water, or three weeks without food.
Byrrah
He can survive only for 10 minutes out of water, unless he uses a special serum that gives him the ability to breathe air. His stamina, agility, and reflexes are reduced when out of the water.