Don't Go in the Woods (1981)

Four young campers, Craig, Peter, Ingrid and Joanie, back-pack through the mountains for a relaxing weekend in the wilderness. They are out camping in broad daylight, while someone else is killing tourists in the woods. Craig warns the others not to go into the woods alone. The hillsides are crawling with fat women huffing up hillsides, nerdy bird-watchers, and young couples.

Most of whom meet gruesome ends at the hands of a deranged and growling back-woodsman with a sharp spike - who announces his presence by shaking the nearest branch and whooping. The 'happy' campers don't see a man and his wife being chucked off a cliff whilst they splash about in the river below. They enter a forest which becomes denser and darker as they progress. Peter and Ingrid fear that they are lost. Something large suddenly comes lunging forward with a gleaming machete. Craig slips dead to the ground as the machete cuts him up. Peter and the others flee screaming into the forest. The rest of the day and terrifying night is spent running and hiding from the maniac murderer who is constantly in pursuit. Meanwhile the local sheriff and his deputy decide they should start to investigate some of those disappearances.