The Safe Haven was the end goal of the Scorch Trials. Although this "safe haven" turned out to be another lie, the island the Immunes escape to at the end of The Death Cure could be regarded as the true safe haven.
Appearance in The Scorch Trials
Near the beginning of the book, the Gladers were told by Janson that they must travel 100 miles across the Scorch to reach this safe haven, where they would supposedly receive the cure for the Flare. However, when they reached the place with Group B, they discovered that it was empty desert. All they saw was a stick jammed into the ground bearing a small flag reading, "Safe Haven."
They were shortly surrounded by a number of pods similar to those which housed the Grievers back in the Maze. But this time, Bulb Monsters climbed out of the pods, and to make matters worse, a freak lightning storm started right above them. The Gladers and Group B began to fight the monsters, as there was roughly one Bulb Monster for each of them. As they were fighting, the real Safe Haven, a Berg, flew down and waited for them, hovering a few feet off the ground. The teens fought their way through the remaining Bulb Monsters towards the waiting Berg, which slowly began to rise into the air without them. They only just managed to board it.