I have been able to download waypoints to DNRGarmin by accessing the GPX file. However, I have only been able to view waypoints.
How can I download tracks?
Within DNR Garmin, you connect the GPS, then make the Track menu option active and select Download. You need saved tracks to begin with and has been used on several varieties of etrex gps units.
EDIT See this thread also.
Correct. With the GPSMap 78 in particular you can no longer use the "Track" or "Waypoints" menus to download data.
The GPS is now visible as an "external" drive. So instead you have to go to File -> Menu -> Load From -> File Navigate to the GPS and select the GPX file. (Change the File Type dropdown option to GPS Exchange Format (*.gpx) first)