A region in a desert where there is a spring or a pool of reliable water.

How water reaches an oasis by flowing through rocks from distant mountains.

Oases are fed by springs flowing from rocks. The source of the spring may be hundreds of kilometres away from the spring, in a place where water is more plentiful, such as a mountain range.

Many oases are very small and no more than a square kilometre in area, but some can be hundreds of square kilometres. The pictures above show the environment and detail of a medium-sized oasis in Morocco.