I've got the first six boxes, then I decided to do something stupid just for the lols. I went to the top of the hill, right next to the big rock and started playing with the boxes, made a stair whith them and was puting one on top of the other to try to get to the top of the rock, unfortunatelly (or fortunatelly) I've managed to put two of the boxes behind the rock, now the level is softlocked for me :).