The landscape photograph below was created with a technique known as high dynamic range, or HDR for short. HDR photo's are usually recognisable by their extreme exposure range. In other words, a greater range of shadows and highlights are visible to the eye when viewing the image, than would otherwise have been seen. This often results in an image that leaves other photographers wondering why their photo's aren't as sharp and detailed.

HDR Landscape 

Camera: Canon EOS 400D / Rebel XTi
Lens: Canon EF-S 17-85mm f/4-5.6 IS USM
Exposure: 3 different exposures, due to the landscape photo being composed from 3 separate images. They were then combined into one HDR image using Photomatix software. See explaination below.
Aperture: f/11
Focal Length: 30 mm
ISO Speed: 100

Nature landscapes including water reflections, tree's, grass and cloudy skies often set the perfect scene for a HDR photo. Furthermore, clearness of the water reflections are due to the images being taken early in the morning before the sun came up. Having an overcast day also added to the effectiveness of the reflections, showing both the tree's and the clouds hovering above, as though it was a mirror.