Includes detailed offshore maps with Bluechart g2 coverage of the USA and Bahamas.Optional BlueChart® g2 Vision card SD data card, which provides high-resolution aerial reference photos for help navigating tricky harbors and channels — or locating spots like area marinas, fuel stops or restaurants. Also allows the GPSMAP 545 to graphically depict a true 3D “mariner’s eye” topside view or “fish eye” underwater navigation perspective.Simple user interface for easy operation-With fewer buttons to push and fewer operational steps to navigate, the GPSMAP 545’s simplified menu format makes it easy for you to see and select the data you want to access on-screen.Simplify navigation with Auto Guidance -Optional g2 Vision auto guidance technology will help simplify your navigation. Auto Guidance searches all the chart features to suggest the best known charted route for navigation. External antenna available separately.