In this week’s episode, “Dr. Linus,” there was an interesting bit of dialogue between Jack and Hurley when they were discussing returning to the Temple. Jack states that if they leave immediately, they can reach the Temple by nightfall. We know that it’s the morning since Hurley says he wants breakfast. So we can assume that it’s about a twelve-hour hike from the Lighthouse back to the Temple.

If we also assume that they were camping in the vicinity of the Lighthouse, they would still be 35-40 miles from the Temple. With an average adult walking speed of three miles per hour, we can calculate that the distance from the Lighthouse to the Temple, based on Jack’s estimation on how long it will take, is at least 36 miles.

This helps us to confirm the locations of the Lighthouse and the Temple at the far southeast and northwest corners of The Island, respectively.

Again, there’s a map with an already-established landmark to make finding the location of the Temple fairly easy:

Even though it’s out of focus, the notation on the right side of the map clearly indicates the position of the Barracks. With this information, we can see that the Temple is located almost due west of the Barracks, at the base of the mountains in the northwestern area of The Island.

This brings us to an interesting bit of dialogue from Rousseau. She claimed that Montand lost his arm “in the Dark Territory.” In season 5 we learn that Montand lost his arm when the Monster dragged him into a hole under the Temple wall. The borders of Dark Territory have never been specifically defined, but if it stretches from the Black Rock to the Temple, then it covers a huge area of The Island. However, if we disregard the statement as the result of Danielle’s somewhat-crazy behavior, this location actually makes a lot of sense.

It is in close proximity to the original French camp, so the team could’ve easily stumbled upon it during their initial exploration of The Island, as well as during their interactions with the Monster.

Following the deaths of her team members, Rousseau would’ve headed south and discovered the radio tower, the Black Rock, and eventually establish her camp in that area of The Island.