From Mo the line runs up the Dunderland Valley at a 1.2% gradient. From Dunderland Station () the line climbs at a 1.8% gradient for onto the Saltfjellet mountain plateau. It reaches its highest elevation just south of Stødi Station (), at above mean sea level, about after passing the Arctic Circle. The line then descends for the next at a 1.8% gradient until reaching almost sea level at Rognan Station (), by which time it has reached the district of Salten. The section onward to Finneid Station () has steep terrain and the line hugs the mountainside, frequently entering tunnels. From Fauske the line heads west to Bodø Station.