I bought a Fenix 5s for my wife as it was reviewed as a high end sports watch with a specifically designed ultratrac mode designed to track long events (+24 hours).If you use the ultratrac mode it returns nonsense results with random 7 mile triangles inserted into the track log.All attempts to get support from Garmin have failed and they constantly fob me off with banal advice and make no attempt to diagnose or fix the issue.
