The Pike River Royal Commission heard on Friday of the value of a bore hole being dug to the area where many of the dead men are thought to have been working at the time of the explosions in November 2010.
The hearings are now looking at the immediate cause of the disaster which claimed the lives of 29 men.
Families' lawyer Richard Raymond has been asking David Reece, an Australian expert who advised the Labour Department's investigative team, if the inquiry would have been aided by a look inside the mine at the point where mining was occurring, known as the goaf.
Mr Raymond said the cost of digging such a hole and inserting a camera would be a fraction of the overall cost of the investigation.
He said it would also prove or disprove its main finding, that the explosion resulted from a sudden release of methane when the ceiling of the goaf collapsed.
Mr Reece admitted a look inside the mine would be useful. While it was out of his hands as to whether or not a bore was sunk, he said he would be happy to recommend it.
