The Siwa Oasis is an urban oasis in Egypt. It is situated between the Qattara Depression and the Great Sand Sea in the Western Desert, 50 kilometres (31 mi) east of the Egypt–Libya border and 560 kilometres (350 mi) from the Egyptian capital city of Cairo. It is famed from its role in ancient Egypt as the home to an oracle of Amun, the ruins of which are a popular tourist attraction, giving it the ancient name Oasis of Amun-Ra, after the major Egyptian deity.

In ecology, an oasis is a fertile area of a desert or semi-desert environment that sustains plant life and provides habitat for animals. Surface water and land may be present, or water may only be accessible from wells or underground channels created by humans. In geography, an oasis may be a current or past rest stop on a transportation route, or less-than-verdant location that nonetheless provides access to underground water through deep wells created and maintained by humans.