Getting to the Hidden Mouth Cave from Mackay, Idaho. Go on the Bar Road to the Pass Creek Road. Drive through the beautiful canyon. Just as you are exiting the canyon, turn right at the cattle corrals (2 large circular structures). Park there and hike the right trail. The trail is a bit steep until the tree line and then it is very steep after that. The good news is that it is not very far. Scramble over the large downed pine and you can see the mouth of the cave. Hiking this trail is best done with a walking stick, especially on the way down.