This unit is both rugged and capable.
The GPSMAP 66st is a turbocharged version of the GPSMAP 64 series. Garmin doubled the internal memory, added connectivity, and beefed up the frame to military specifications for thermal and shock resistance. On the "t" models of each, they also included preloaded topo maps. We loved the 64 for its functionality and ruggedness, and we love the 66st even more. So much so, we gave it our Editor's Choice Award.
The GPSMAP 66st has excellent reception for a few reasons. First, the actual construction of the antenna is a quad helix design, which is quite sensitive, and better than some other designs in tree cover or low satellite angles. The 66st also uses three different satellite systems: GPS (North America), Galileo (EU), and GLONASS (Russia) allowing the most amount of satellites for triangulation, making this a really accurate unit.
In the field, we found the 66st to live up to its reputation. When mapping old mountain biking trails in Southwestern Utah, we were able to leave and easily pick up the trail again, rather than being forever lost among the sea of junipers.
This was was the only unit we tested that included the european Galileo satellite network in addition to the GPS and GLONASS networks, giving the unit even more satellites to connect to, increasing accuracy.
Ease of Use
The GPSMAP 66st was one of the easiest units to use straight from the get-go that we tested. All the buttons are large and have easy to read labels on each one. Unlike some of the other units, the 66st buttons are pretty straightforward and there are enough of them for each to have a distinct function in a particular setting.
As the functions get more in-depth, the controls do get more complicated, but that's to be expected. Some of the pairing with other devices and apps took a lot of back and forth registration and pairing, which was a hassle, but only a one-time inconvenience.
While some folks may prefer a touchscreen, we really liked the big buttons on this unit, especially in the cold. The 66st functionality works great regardless of conditions, whether it's freezing or wet. The buttons are big enough to push with gloves on, and there's no touch screen to get wet and inoperable. Like most of Garmin's handheld units, it's rated to IPX7 water resistance, which means it's good to go for rainstorms or snow, just not full immersion.
Unlike some of the more basic models, the GPSMAP 66st has an electronic compass to determine direction even when you're stopped, and the map auto-orients as a result.
With the transflective TFT display on a three-inch screen, the 66st is really readable, even in sunlight, which is really nice on snow or a bright, sunny day. The 240 x 400-pixel display is nice when viewing photos or satellite imagery on the Bird's Eye function, but otherwise, we'd be hard pressed to tell much of a difference otherwise. Unlike the touchscreens, the 66st does not rotate from a portrait view, but it wouldn't really make sense to on this unit.
This unit is about the size of a smartphone, but a bit thicker.
Like most of the button operated GPS units we tested, the 66st isn't quite as responsive in function as the touch-screen units like the Oregon 700, but it wasn't slow enough to be noticeable or create any issues from the slight lag. It did actually draw maps quite fast, fast enough for the maps to be redrawn almost as fast as a pan across the map, depending on the scale. It also can go through a lot of data quickly, and it doesn't take much time loaded new big route files or bird's eye satellite images.
Weight and Size
At eight ounces, the 66st is the second heaviest unit in the review. On one hand, eight ounces isn't that much. On the other hand, it's half a pound, which seems like a lot. It fits into most jacket pockets, but it's big enough that hiking with it in a pants pocket is annoying. This is definitely not the unit for the ultralighters out there, but rather a serious tool for a lot of information gathering.
The GPSMAP 66st fits pretty well into a larger chest pocket, but is a bit big for pants pockets.
The GPSMAP 66st is a highly versatile and accurate GPS unit. It's accurate, easy to use, and seems quite bombproof. The battery pack is simply two AA's, which, although not rechargeable, are easily found around the world. Lithium batteries make this thing cold resistant too, and with the big buttons, it works great for ski touring or other wet and cold activities. We think this thing could be used in any given situation where a handheld GPS is appropriate.
The best thing about the 66st is the way Garmin paired accuracy, ease-of-use, and a heaping helping of memory. For professionals who need to use a lot of data on a GPS unit, but don't have the budget for a Trimble, this is a good option. With the 64GB microSD cards now available, the 66st could carry up to 80GB, which is way more than we think we could ever use in the lifetime of a unit, without deleting anything.
This GPS is pretty easy to use with gloves, and with lithium batteries and expedition mode did quite well in cold weather.
Provided you're willing to shell out for a high-end GPS unit, this thing will go anywhere. Skiing, backpacking, field work, you name it. It can be put in expedition mode to save battery life on long trips; and can be soaked, knocked, dropped, and the thing keeps kicking. With the military built specifications this thing is rugged, and if you add a lithium battery pack the GPSMAP 66st will word in nearly any environment.
At $450, the GPSMAP 66st is the third most expensive unit in the review. The one feature that would have made this more expensive is a touch screen. If you do need the functionality of the 66st, then it's worth it for sure. If you plan on downloading your own maps anyway, you can knock $50 off and just get the 66s model, which for what it is seems like a pretty good deal. However, if 16GB or more and wifi capabilities are excessive to you, the GPSMAP 64s is $150 cheaper and fairly similar.
For a really capable, really durable GPS unit, the GPSMAP 66st is an excellent choice. It holds more data than anyone but a really dedicated field researcher on a long trip could use, can connect to smartphones and wifi, and can view the world via maps or satellite imaging. The 66st isn't cheap, but you get what you pay for: a burly, accurate, featured unit; good enough to earn the Editors' Choice Award for Most Reliable 4 Season GPS.
The GPSMAP 66st is an excellent device, and can withstand storms and sand. So far, this is the most capable and robust device we've used.