Using the Garmin GPSMAP 66 in the Field

I have a GPSMAP 66S, but what I have to say here applies to the 66ST as well- the only difference between the models is that the 6ST adds Garmin Topo maps. I prefer to load my own maps from, which are more detailed than Garmin's 100K maps and are free. So, when I refer to the GPSMAP 66S below, I mean both models.

Before I get started, let me say that the positives in this unit far outweigh the negatives, at least for my use. The core function, that of locking onto satellites and determining your position, is significantly improved over the already excellent GPSMAP 64 series.

Garmin GPSMAP 64 Series

Garmin GPSMAP 64

The GPSMAP 64 series is a much-anticipated update of the 62 series to include reception of the Russian GLONASS satellites. As already proven by the Garmin Oregon 600 series of touch screen trail GPS units, adding GLONASS to the US GPS satellites slightly increases the accuracy and significantly increases the reliability of the navigation fix. With more satellites to use, the Oregon 600 maintains its satellite lock under partially obscured skies, such as in canyons and heavy forest cover. Having more satellites available also makes it less likely that the accuracy of the fix will suffer from poor satellite geometry, which can happen if all the usable satellites are in a line.

Much-anticipated? Well, not all of us like touch screens for field use. Although the Oregon 600 series is vastly improved over its predecessor 400 and 500- series, I still prefer buttons while wearing gloves and in cold weather.

All of the 64-series units support additional Garmin maps, as well as custom maps. The base 64 model comes with a basemap, and 250,000 preloaded geocaches from The 64s adds an electronic compass and altimeter, and the 64st adds TOPO U.S. 100K maps.

I recommend the 64s, since there are plenty of free, high-quality maps available from as well as other sources.

Garmin 010-01199-00 GPSMAP 64 Worldwide with High-Sensitivity GPS and GLONASS Receiver

Garmin GPSMap 62s

Garmin GPSMap 62s

This is my favorite Garmin trail GPS receiver at present. I use it for trail mapping as I work on my hiking guides. If you need custom mapping and other advanced features and don't like touch screens this is your receiver. It comes preloaded with a worldwide base map, and detailed topo maps can be added, including Garmin 1:24000 topos and satellite imagery, as well as free maps.

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