Re-entry into Pike River has gone ahead as planned today.
An attempt to go back in the mine two weeks ago was aborted at the last minute after unusual oxygen levels were detected.
Twenty-nine men died after an explosion in the mine on November 19, 2010.
Pike River Recovery Agency chief operating officer Dinghy Pattinson, as well as mine worker Kirk Neilson and mine surveyor Chris Coll, opened the doors and went inside.
A tweet to the Pike River Recovery Agency says families of the men killed nine years ago let out a big cheer as the three returned from the mine today.
Anna Osborne, who lost her husband Milton in the explosion, said outside the mine today, "It's actually quite emotional seeing these families turning up knowing that it is actually going to happen today and that plug is going to be pulled from the seal."
"We've all been through so much and this is the start of something good for the families, finally, and I'm sure a lot of them will be quite relieved to know that today is actually happening."
Sonya Rockhouse, who lost her son Ben in the mine disaster, added, "I just can't believe it's finally here. It's just the most weirdest feeling."
"It's been a long time, and we've stood on this road many times – many, many times – and just felt nothing but despair and no hope, and now, I can look up at those mountains and think, 'Crickey, you know, we're almost here."