For me, an oasis only comes to mind in the imaginary sense: The kind that movies depict when the protagonist is lost in the desert and sees a lagoon in the distance, but nothing is ever really there. But Huacachina Oasis in Peru is definitely a reality. Though it's not in the heart of a desert (it's a few kilometers from downtown Ica, which rests outside the desert), it certainly feels world's away from anything.
Relax by the palm-tree bordered lagoon, or adventure out into the desert. Surrounded by tall sand dunes, Huacachina is the perfect adventure junkie's escape: Take an adrenaline-pumping dune buggy ride, go sandboarding, or just enjoy the spectacular scenery via horseback. And if you want to stay overnight, there are plenty of low–price options (as in $4-$9/night!).