Under spiral mountain?

[torrentstorm]

I were hanging around SM for a hour trying to glitch under.
Where do i do it?

[BanjoFreak12]

Trying to break the barrier? There are a few ways to. Either go onto the hill behind Grunty's Lair, and on the right side of the hill, there should be a small break in the wall that allows you to whack at to get through. (Kind of like the break through the barriers in SDT & ToT) You can also use the method mentioned in the BK:N&B forums where you create a vehicle of just a grenade turret, turn it on its side, turn the Turret to the point where you can see underground, jump out, and switch to a flying vehicle.(Otherwise you'll hit the boundary and reappear.)

[kirbyfanner]

As BanjoFreak said, I used the turret method. I did it right over by Banjo's house, the factory is practically beneath it. If you do it somewhere else, just look for some smoke in the distance.