Where in the dig site do you dig for coins in club penguin?

Go to the cave where there is the machine where you throw snowballs in to light the cave. Wear only the orange helmet, nothing else. If you don't have an orange helmet yet, they give out orange helmets for free, right where there are orange helmets hanging at a wooden post by the entrance. Go to the brown dirt part and dance, and you will see that your penguin will be drilling. Move to several other places if no more coins come out or if no coins come out at all for a while.