The 2009 film starring Viggo Mortensen utilized locations in Louisiana, Pennsylvania, Washington State & Oregon to create the bleak atmosphere of a post-apocalyptic world.
The opening scenes along the hillside of dead trees was filmed near Mt. Saint Helens, WA, within the national park. Similar scenery is used in The Vanishing.
The log-covered lake is Spirit Lake, within Mt. St. Helens National Park. The mountain itself is concealed in the clouds in the shot.
The sequence on the road outside a tunnel was filmed on an abandoned stretch of highway NE of Breezewood, Pennsylvania. The tunnel seen in the film is known as "Ray's Hill Tunnel", and is now being converted into a bike trail.
Coordinates:
40° 1′ 5″ N, 78° 12′ 14″ W
The waterfall that Man (Viggo Mortensen) and Boy (Kodi Smit-McPhee) go swimming in was a combination of two different ones. The shot where they see a rainbow was Latourell Falls in Oregon.
However, the actual pool they swim in was Horsetail Falls, also in Oregon.
When the boy and his father finally reach the coast the film crew used Fort Stevens State Park near Astoria, OR. The Peter Iredale shipwreck on the beach is featured in multiple shots (including the one above).