Red Rock Pass is an area in The Land of Ooo that was shown in the episode "It Came from the Nightosphere." Marceline said that her dad can only get through the mountains if he passed this area. This is where Marceline and Finn found her dad taking the souls of ants and singing Stomping on Ants. It was then Marceline attacked him immediately and Finn tried to push the rock, as seen on the picture, on Hunson. This attack lead to failure for Finn and Marceline. This might be a place that appeared in "Susan Strong," where Susan crushed a rock. The setting looked similar to that of Red Rock Pass.
The place looks like a crack on the earth, such as the aftermath of a earthquake. The rocks here are red and many skulls of large animals can be found here. The place is also very mountainous and has many cliffs. It looks similar to the Grand Canyon.