i-Boating maps web-api allows other companies to display our charts and  HD lake contour maps on their website. The API allows overlaying custom GIS data (line, points, areas) on top of i-Boating nautical charts base map. Check out the SDK examples at the link below. http://gpsnauticalcharts.com/main/sdk-examples.html I've included below a sample application that show lat lon on click.