The International Appalachian Trail extends across the west coast of Newfoundland from south to north. As of the time of this writing (Fall 2016), much of the trail follows the Trans Canada Trail (former railbed), paved roads, ATV trails and logging roads. This is a work in progress and some information is available online from the folks at International Appalachian Trail Newfoundland & Labrador.
There are also many loosely defined routes on Newfoundland’s west coast listed on Clarence Pelley’s site; Cormack Expeditions. I’m unable to discern if some of these routes are in fact also the IAT-NL. In any case, Clarence details several routes ranging from 3 to 55 kilometers in length. Note that these all appear to be trackless backcountry treks – no trail, but route finding with the assistance of detailed text – so navigation skills are required.