For boaters and watersports enthusiasts who want to run with the best, the rugged GPSMAP 78s features a 3-axis compass, barometric altimeter, crisp color mapping, high-sensitivity receiver, new molded rubber side grips, plus a microSD card slot for loading additional maps. GPSMAP 78s comes with built-in worldwide BaseMap, so you can navigate anywhere with ease. And, like the rest of the 78-series, 78s is water resistant (IPX7) and even floats in water. GPSMAP 78s has a built-in 3-axis tilt-compensated electronic compass, which shows your heading even when you?re standing still, without holding it level. Its barometric altimeter tracks changes in pressure to pinpoint your precise altitude, and you can even use it to plot barometric pressure over time, which can help you keep an eye on changing weather conditions. With GPSMAP 78s you can share your waypoints, tracks, routes and geocaches wirelessly other compatible device users.