How To Get The Marathon Man Achievement In Halo 3

If you're a total completionist, you're going to want to learn how to get the Marathon Man achievement in Halo 3. Not only can you add to your overall gamerscore, you're also going to be that much closer to satisfying all of your obsessive compulsive disorders. To complete the Marathon Man achievement, you need to locate all seven terminals and read through the information they provide.

Here are all 7 locations needed to unlock this achievement:

1. Start 'The Ark' mission. Go through the level until you enter the first tunnel. Look to your left - the terminate is located in the hallway.
2. Activate the light bridge during 'The Ark' mission. Turn completely around and locate the stairway leading up. The terminal is at the top of the stairs.
3. Defeat the Scarab and go inside the building. Once you find a narrow hallway leading down. Enter the large room beyond the hallway, and look behind the ramp. The terminal is located behind the ramp.
4. Start 'The Covenant' mission. Enter the first tower. Jump onto the elevator platform and jump the second gap. Find the terminal in the next room.
   
5. Fly the hornet to the second tower. Land the hornet and enter the tower. The terminal is directly inside the tower.
6. Enter the third tower. Locate the elevator platform and jump across. The terminal location looks exactly like the location in step 4.
7. Start the 'Halo' mission. This is the last level of the game, so you aren't completing the Marathon Man achievement early on. Find the first tunnel area - you'll know you're in the right one if you see steel beams with open sky above you. Drop to the ledge below and turn 180 degrees. Find the hidden passageway and follow it until you reach a door. Turn left and open it up to find the final terminal and get the achievement.