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 IPX 7 waterproof to withstand the accidental dunk or splash in the lake.