Don't go immediately after the buried gold in the middle, or you'll be trapped between two groups of two at the bottom. Wait on the beginning platform until they go as high up the ladders as possible, dig a hole to drop down at the right, and run to the ladders at the right-hand end. It becomes much easier if you can lure two of them into dropping into the holes at the bottom center.
Get past them all one at a time. Lure them to the top. Go down the left-hand ladder and run as fast as you can to the bottom right to dig six holes for them to die in. Run up to dig as many holes as possible, then do a little jig on the bottom-right ladder so only one of them dies. Go down, dig two holes for them, run over them, get past the one higher up, and go get the rest of the gold. If you do it right, you can get one or more to fall in the tall thin (upside-down T-shaped) tunnel and stay there. Or you can dig out the whole 3-by-3 block at the bottom, dig a bunch of holes for some of them to die in, and go back to the left of the block before it fills in. Then go up and over, go past whichever one(s) are left down there, then get past the ones higher up.
As much as possible, dig only the highest two layers you can get them to fall into, and don't dig any more holes than strictly necessary.
Keep separating one from the pack at the bottom right. Hang from the rope until it goes up the ladder, then drop and run and dig holes to get past the other two.
Another trick on this one is to get all three guys on the left ladder, while you're on the middle ladder (the one on the bottom). From there, drop down and dig three holes on your left. The guys will run into the holes. When the first one jumps out after you, run up the ladder and dig a hole to your left. If you do it right, all three will follow you and be stuck at the top of the ladder, while you clean up a bunch of gold.