Starting from Karamea Bend Hut head west along Karamea Bend Hut to Crow River Track. After 5 minutes cross the Leslie River and then make your way up the Karamea River bed on an unmarked route.
This takes around 7 hours to get to the Roaring Lion Hut which sits at the confluence of the Beautiful and Roaring Lion Rivers. You'll need to cross many rivers.
NZTopo50 map sheet: BQ23
Grid/NZTM2000 coordinates: E1552333, N5438998