Though possible on any run, it's recommended that you tackle Mount Robson in the Rockies for this achievement. The gold medal is earned from two complete runs down the mountain, plus a small chunk of a third run.
There is no advantage gained by going fast on this run, nor earning big points and pulling off tricks. You will be without armor so just take it methodically and avoid the trees. As such, a low level, slow board is recommended.
Once you have survived the first run, the second will be easier. Just beware that on the lower half of the mountain, during your second run, visibility will reduce and there will be a pattern of three fallen trees to avoid.
Note: Has to be in Explore Mode.