The latest addition to Garmin’s vast range of GPS options is geared towards outdoors types. Think of the 600 series as a-go-anywhere, waterproof GPS unit that features both marine and automotive GPS functions by sensing the type of vehicle through the mount and then showing to the appropriate function. So when the 640 is in the car mount, it will function a lot like Garmin nüvi with road maps and such, but when snapped into your boat, navigation maps along with underwater 3D bathymetric contour perspective appear. In addition, there is XM radio access including the WX Satellite Weather data and XM NavTraffic with an accompanying subscription. All this convergence comes with the international 620 model going for $999 and the U.S. destined 640 carrying a $1,199 MSRP.