This article contains plot spoilers for the 2017 series of Twin Peaks.
Somewhere close to Jack Rabbit's Palace on the mountain, there was a portal connected to the Fireman's home. A pit with a golden substance, very much like the black substance outside the entrance to the Black Lodge in Ghostwood National Forest, could be found here.
During a trip to Jack Rabbit's Palace, members of the Twin Peaks Sheriff's Department – Andy Brennan, Bobby Briggs, Hawk, and Frank Truman– found Naido on the mountain. Andy saw a vortex, or a portal, form in the sky and he was transported to the Fireman, who showed him a series of images before he was transported back to the forest. But now he appeared by Jack Rabbit's Palace where the others were already waiting. Their memory of the event seemed foggy to them.
The doppelganger of Dale Cooper traveled to the mountain after receiving coordinates from the tulpa of Diane Evans. He vanished and was transported to the Fireman's home, then to the Sheriff's station in Twin Peaks.