Thirty-nine miners were faced with a 10-hour vertical climb after they became trapped deep underground in eastern Canada.
They got stuck below the Totten mine in Sudbury, Ontario, on Sunday after the lift system was damaged.
The miners were said to be unharmed, with access to food and water.
Rescue efforts were under way on Monday and the exhausted miners were using harnesses to keep them on the ladders for the 1km (0.6 mile) climb.
Shawn Rideout, chief mine rescue officer from Ontario Mine Rescue, told the Toronto Star newspaper that the workers had already been in the mineshaft for more than 35 hours before beginning their ascent.
He said the ascent could take up to 10 hours for workers to complete but there were rest stops every 100m if they needed to take a break.
"Everybody is safe, they're all in good spirits, we have no reported injuries. Our plan is to get them to the surface in that same form," he said.
The miners have also been able to speak to their families on the phone.
The lift system became inoperable on Sunday after a heavy scoop bucket crashed into it and blocked the shaft.
Totten mine is run by Brazilian firm Vale and employs some 200 people to produce copper, nickel and precious metals.