Long Weekend (1979)

A couple that are on the verge of not being a couple any longer take a trip to the Australian coast for a weekend, bringing their strife and noise with them. Their situation is so tense that they don't notice how careless they're being and they continually damage the environment in small ways. Things start to happen that suggests that there exists a force of malice towards them and at some point it becomes apparent that perhaps the ecosystem is actually attacking them, presumably to protect itself. It's never made explicit because this is a well made film that doesn't insult the viewer's intelligence by trying to spell out something that couldn't really be known if such a story is to be told honestly and from a human perspective. Great acting and cinematography, a flawless doom-laden atmosphere, constant tension and excellent, memorable use of sound ensure that this Australian film is a classic of the 'nature fights back' subgenre of survivalist horror. There's nothing else quite like it and several scenes have never left my mind.