The line carried some passenger traffic, but was mostly known for the roaring sound of the steam locomotives making heavy work of travelling up the steep grade to Glen Massey, and the squeal of the brakes as it brought heavy coal down to Ngaruawahia.
The line featured a number of timber bridges as it crossed and re-crossed the Firewood Creek on its way, including one large trestle. Look under each the new walkway bridges, and you will see the remnants of the wooden rail bridge piles as you cross.
The line closed as the collieries wound down and road transport improved, in May 1958. The lines were lifted and the embankments slowly reverted to bush, until the Hakarimata Rail Trail was developed in 2008, along a small portion of the earthworks. It is planned to extend the walkway further towards Glen Massey, which will further open this historic artefact for public view.
You are looking for a 400ml click-clack box in one of the cuttings made to level the line through the hills, it is within one step of the flat, but do keep an eye out for the ghost of Bb222 roaring down the hill from the west, past you with a full load of coal trucks.
Once you have found this cache, it is only a short walk to the nearby Water cache, and there are many more caches on the Hakarimata walkway above you.