How you get inside doesnt matter. Everything ranging from alternative entries to making temp openings and collapsing them with [[shaker_orb|orbs]] works. All that matters is you mine the cave floor deep enough and then mine straight out. Just make sure you have some means of restoring [[stamina]] nearby.
Even if you get the entrance worng on the first try. Do not worry. Simply collapse the tile with an orb or Mag priest and try again.
=== Surface mining ===