A drilling rig boring an 8-and-a-half-inch hole into the Utah mountains may offer the most hope to six miners trapped 1,500 feet below ground.
The mine's owner says it could reach the cavity where the trapped miners are thought to be by Friday.
"That is where our greatest hope is and that drill is drilling, and hopefully we'll be down in two days," said mine owner Robert Murray.
An aerial view shows what rescuers are up against.
The miners are buried deep inside the Crandall Canyon Coal Mine, three-and-a-half miles from the entrance.
Besides drilling two holes down from the surface, rescuers are resuming the underground efforts.
They're using wood, steel posts, and cables to re-enforce the walls of the mine as the move towards the trapped men.