High Ground vacation

From Halopedia, the Halo wiki

Method 1

(You need to be on Forge to do this, and have at least two players.)

To get out of High Ground Player 2 must get into a Mongoose side seater. Player 1 then turns into Forge mode and picks up the Mongoose (You HAVE to be in side seater to do this, or you will climb out). Player 1 then pushes it behind the rocks on the left (if they are facing towards the sea) and Player 2 climbs out. Then Player 2 turns into forge mode and can climb up to the edges of the map.

Method 2

Spawn a teleporter outside of the map, and spawn a second one out on the map. This way can be easier if you don't understand the first method.