The Covenant vacation
From Halopedia, the Halo wiki
Getting out of The Covenant(level)
1st method
On the level The Covenant, it is possible to get out of the map. When you get to the first tower, do not enter. Instead, kill all the enemies outside except for the shade turret on the hill. Get up on the hill and kill all the enemies. Make sure you crush the shade turret with a ghost. What will remain is the shade turret's base. Drive ghost(boosting and pressing A button) up to the base of the shade turret and land on the the tower ramp thingy. This may take a few tries.
After landing, continue using the ghost to climb up the ramp until you reach a wall in the ramp where the ghost cannot pass. Get off the ghost, jump on it and jump onto the top of the wall. then proceed up the ramp(there is a location here where you need to crouch) and jump onto the snowy edge. If you look in the distance with your zoom, you will see a small structure. You have now gotten out of the map but beware, for if you pass the structure, you will die.
2nd method
When battling the two scarabs, go onto one of them. Make sure you have a brute shot. Proceed to its power core, and shoot it once with the brute shot. Then melee it with the brute shot. The scarab will despawn and you will first be teleported to the ground, then fly out of the map at a high speed. You will die soon after because of a death barrier.