Atkinsons's or the 3rd is not as steep as the 1st or 2nd Tree runs.
It is the second run past the patrol shack on your left as you come down the ridge from the top of Shirley Lake Express.
There is a narrower option on skiers right of a grove of trees in the middle of the run.
It merges with the 2nd and 4th tree runs and continues to the base of Shirley Lake Express.
Most skiers will bear right at the end of flatter section to finish off the run.