Increased luminosity and contrast, satured or desatured separately water, sky, trees and mountain.
At the end increased luminosity and decresed contrast.
Using photoshop CS2, I did some adjustements to your photo.
1-Using shadow/highlight option at 20%
2-Using magic wand select the sky
3-Using photo filter cooling filter at 30%
4-Inverse the selection
5-USM at 50%, .3 and 0 once
6-save the file