This offshore mariner's navigator flush-mounts easily in your boat and sports preloaded BlueChart g2 maps for the coast of the U.S. and Bahamas. The GPSMAP 540 also features a 5" QVGA display and simple, straightforward buttons and menus. You can add the optional BlueChart g2 Vision SD card for even more enhanced features. The 540 has preloaded detailed maps covering all U.S. coastal areas and the Bahamas. For other areas, the 540 has a worldwide basemap with satellite images in place of more traditional maps. The SD card slot makes it easy to add additional maps without connecting to a computer. And with just a few buttons and a simple, intuitive interface, the 540 makes navigating your way through the water easy.