Those are Slovensky Cuvac The Kuvasz has a tad stockier build, bit longer fur and normally curled or at least wavy fur. The Great Pyrenees have a way stockier build with bigger head and looser skin, especially on the muzzle.
Hope I could help (I'm quite addicted to flockguardian dogs and dogs in general)
I would say that they are golden retrievers: wikipedia article Their heads aren't so big as great pyrenees has and their fur colour is more like golden retrieverish. But hey this is a very nice shot, beautiful dogs.
Well you saw them in nature, so I guess you're right then. But it isn't so long time ago when I saw a great pyrenee-dog and it looked completely different than these two dogs, so maybe this breed is just unknown. You're very welcome.