Another case for having access to the recorded data (gpx/nmea etc), I find it quite awkward to see contour line drawn perpendicular to the shore line..

Also, Garmin should implement some way to designate a certain track (which represents a contour line) as the shore line. If we are going to map an unknown lake, it certainly helps to have the shoreline available first. This shoreline tracing can be generated from a lot of available satellite imagery, which then can be used as a rough shoreline of our target lake. For what it's worth...