Fallout: New Vegas locations project
Northern Passage is a location in the Mojave Wasteland located north of North Vegas. It serves as the starting point for the Fallout: New Vegas add-on Honest Hearts, also serving as a checkpoint for the path to Zion.
A grave and a hollowed-out rock containing random minor loot can be found near the cave entrance. The rock may have "The sun is killing me" written on it. The passage's interior consists of nothing but wooden supports and lanterns.
Before Honest Hearts is downloaded, the Northern Passage is covered by a barrier of fallen rocks. But when Honest Hearts has been installed, all the rocks have been removed.