EDIT: After exploring the tunnel, it seems that it has had repercussions in other areas of the game, like most of the floor by the Quarry, the one with all the Deathclaws, is only showing in an un-rendered state, and, when walked on, you fall through, into a small area of water. Swimming to the end of the water teleports you back up, but you can simply continuously fall, or even get stuck in rocks. Reloading the game will fix this, however.