Product description from Garmin:
If you’re a devoted mariner or serious outdoor enthusiast, our new GPSMAP 76S is the GPS/mapping unit for you. The "S" in the product name stands for "sensors", because the GPSMAP 76S incorporates a GPS receiver, barometric altimeter, and an electronic compass that deliver precise location, elevation, and bearing information to take adventurers as high or as far as they want to go. The unit also contains a basemap of North and South America, including major highways, thoroughfares, rivers, lakes, and borders, with plenty of memory (24 MB) for downloading MapSource data. It's also waterproof and floats in water - and its larger screen, increased readability, bigger buttons, and rugged design make this unit at home in even the harshest conditions.