The Garmin GPSMAP 78 1.7MB Marine-Friendly Handheld GPS Navigator
features crisp color mapping, high-sensitivity receiver, new molded
rubber side grips, plus a microSD card slot for loading additional maps.
The card slot is located inside the waterproof battery compartment, so
you don't have to worry about getting it wet. It comes with built-in
worldwide basemap and 1.7MB of map storage space. GPSMAP 78 also
supports BirdsEye Satellite Imagery (subscription required), that lets
you download satellite images to your device and integrate them with
your maps. And the unit floats in water, and is IPX7 waterproof to
withstand the accidental dunk or splash in the lake.