The Pike River re-entry team successfully passed the 170-metre barrier on Tuesday afternoon.
The 170-metre barrier marks the furthest distance the recovery team had up to now been inside the mine.
"That was a long time coming," chief operating officer Dinghy Pattinson says.
"Last time I was on the other side of that 170, I was part of the mines rescue team looking for where to put a wall. And that was back in 2011. So today was pretty significant for me."
The team checked for any hazards, inspected the state of the tunnel's roof and walls, and had a brief forensic scan.
Pattinson says this initial scan did not reveal anything unexpected.
"We know we'll have to do some work on the roof and ribs as soon as we get the barrier out of the way in January. But it's looking pretty good," he says.
The next phase will see a push through the remainder of the 2.3km drift, with forensic examinations happening along the way.
"We need to find out as much as possible about what caused 29 men to go to work and not come home," Andrew Little, the minister responsible for the Pike River re-entry, said earlier this month.
"Now the agency will proceed with what it considers to be the best and safest way to ventilate the drift."
Pattinson says the entry point will be shut and secured over the Christmas closedown.
"It will give us more time to monitor the underground environment - before starting to remove the barrier in the new year."
