After having watched Vincent Price's magnificent performance in The Last Man on Earth (1964), I had high hopes for The Last Woman on Earth. My expectation was to discover a 1960's empowered female who beat the odds in the apocalypse and sent all of her enemies packing. No such luck!
Last Woman on Earth is a Roger Corman directed low-budget sleeper. IMDB says it's a drama/horror/mystery but I would be hard pressed to find any one of these elements in the film let alone all three of them. The plot is simplistic and predictable. You see everything coming from a mile away. Furthermore, it reads more like a bad, slow-paced soap opera rather than an exciting adventure.
Betsy Jones-Moreland [Creature From the Haunted Sea, bless her heart] is Evelyn Gern, the woman at the heart of the story. She is far from empowered and keeps flitting back and forth between what appears to be the last two men on earth. All three are weak in the acting department but to their credit, they had very little to work with in terms of great dialogue.
The basic gist of the story is that Evelyn, her husband, and a mutual friend are on vacation in Puerto Rico. They go scuba diving and when they surface for air they discover there was a temporary depletion of oxygen in the earth's atmosphere (which is never fully explained) and everyone they encounter is dead. That's all you need to know and that's about all that really happens in the film. No gore or horror elements to be found. Just straight up melodrama.
If you are expecting a nice, little horror/mystery film, then look elsewhere. This one was disappointing to say the least.
For more info check out the film's entry in IMDB.