The Greenland GPS app, available for free for Apple and Android, contains maps and trail guides for the 160-kilometer Arctic Circle Trail (between Kangerlussuaq airport and the town of Sisimiut on the west coast, with lakes, fjords and 300- to 1,000-meter-high mountains) and for trails in the South Greenland Trails area (between the airport at Narsarsuaq and the town of Narsaq, ranging from flat fields to 1,700-meter peaks and featuring Viking ruins).
A phone’s GPS will update the hiker’s progress on the map. Maps, which have info on historic sites and show locations of overnight huts, can be downloaded for offline use.