The Ruins (2008) trivia:
All the outdoor scenes were shot with natural light.
Director Carter Smith had just purchased a copy of the Scott B. Smith novel and started reading it, when he received a call offering him the film adaptation.
The film takes place in Mexico during summer, however it was shot primarily in Australia during the winter. Heavy coats were provided for the actors between takes with water and olive oil sprayed onto their bodies to simulate sweat.
The film rights were sold before the novel was published.