The second phase of work to re-enter the Pike River mine tunnel on the West Coast has begun.
Explosions at the coal mine in November 2010 killed 29 men.
The Government has approved a seven-phase re-entry programme that will allow mines rescue staff access down the mine drift as far as a large rockfall.
The mine's owner, Solid Energy, says the first phase - the plugging of a ventilation shaft that runs 100 metres vertically down into the mine - is almost complete.
The second phase, the drilling of the first of three boreholes that will eventually be used to flood the mine with inert nitrogen, has begun.
