PREMISE
An oasis is a lush green area in the middle of a desert, centred around a natural spring or a well. It is almost a reverse island, in a sense, because it is a tiny area of water surrounded by a sea of sand or rock.
Oases can be fairly easy to spot—at least in deserts that do not have towering sand dunes. The sight of an oasis on the horizon has been a very welcome one for desert travellers.
