Originally posted by another user
You don't need to shotgun jump..
Just strafe from the turret to the dumpster, then sprint jump from wall to wall.
Lie down, move to the left until you can't stand, move to right until you can't stand and repeat until you start elevating.
Then sprint jump onto the opposite building and walk out of the map, then go right off the edge and keep sprinting to easily get Marathon and Lightweight pro.
Yes to get to the elevator you just jump but the outside part im talking about is where you are by the Seals spawn and under it. You cant just fall down from the building you glitched on and run over to the building by the water because if you fall in you die. With the shotgun jump you shotgun outside of the chicken farm and you can go underwater from there and you dont die and you can go everywhere under the map without dieing.