A mine tends to go underground based on pit design limitations...

A mine tends to go underground based on pit design limitations and grade, but i believe 300m is about it. Some mega pits can be much deeper.
It also comes down to grade of course and the underground component requires grade. It is still very early days for a full definition of what lays beneath here. These results prove that gold extends deeper and along strike (previous news).
If EAR finds a decent underground, that will be more than enough for NST to take this puppy out. Ear can also hit on real tonnes from the other 7 targets and the new 20km long conduit. EAR will just keep growing resources and the wild card remains at the end of the drill bit. One of their targets is a 1m ounce play so anything can happen. Its not getting any smaller.