When you are using your Garmin make sure that the Map Datum is set to same Datum used on other mapping programs and maps that you want to use with it. Otherwise, you could be up to a mile off the location where you make a waypoint. Consider this: Map Datum is the method used to make the map, ie. conic projection, Mercator projection, etc. is way land/water surface is stretched to make it flat. This is a major mistake that many folks make by not using Map Datum settings on the GPS.