Vipera berus

I went trad climbing today to the little-known Slovenian mountain called Kogel, and during the walk to the wall we ran into this fellow, the common European Adder (locally known as a Gad). I've seen snakes before in the wild, even poisonous ones, but this one is the biggest so far (as well as the closest). We estimate that it was around 60 cm long, though his hiss was surprisingly loud (you could hear it clearly from about 10 meters away).