If you have a compass, just look at it. Without these tools, a simple way is to see which side of the forest is more lush, or which side of the tree rings on the stump are more spaced, so this side faces south, and then it is easy to find that it faces north, with its left hand facing west and its right hand facing east.

Another way is to aim the watch's hour hand at the sun by relying on the sun and the watch. At this time, an included angle is formed between the hour hand and the scale 12, and the direction indicated by the bisector of the included angle is due south.