There are no external (i.e. environmental) objects needed to solve this one.
Three Canteens
Two men wandering in the desert come upon a trail. In hope of finding help sooner, they decide to split up, each taking half of their remaining water, and to set off in opposite directions.
They have only one 14-cup canteen full of water, and two empty canteens that will hold nine cups and five cups, respectively.
The only way for them to measure water is by pouting water from one canteen into the other until the first is empty or the second is full.
How can they measure seven cups into each of the two larger canteens?
(from a puzzle magazine)