Roger Corman has the distinct title of "master of low-budget", which is really sad because the connotation of low budget usually equals bad movie. But many of Corman's films, while having their faults, are still pretty good. Exhibit one: the Last Woman on Earth.
Here we have a tale of a beautiful lady trapped to the arm of an unloving and rather brutish husband who's only worried about money. Escaped to a southern island to avoid a legal entanglement, the couple are joined by his lawyer who is instantly smitten with the charming (if not disturbed) female. As they are scuba diving, the world goes up and everyone dies. Once emerging they realize the air is very thin and if not for their scuba gear they would suffocate. The trees eventually regenerate the air they need to survive, and the trio find themselves alone on an island swarming with the dead. From there we explore the relationship between each man and the woman and the dissolution of the friendship because of it.
With this tale, Corman has brought real life rationality and emotions to being the potentially last survivors on Earth, also introducing real life concepts that big time Hollywood films choose to ignore (signatured by an unhappy ending). An interesting watch and well worth it.