i have a garmin vista C with bluecharts. decent detail of bathometry
here is track from the gps in mapsourse, it has a little better detail if you zoom in but not much on bathometry
La Jolla mapsourse bluecharts on garmin vista gps
San Diego bay from my sonar (HB 597 CI HD DI)in mapsourse with bluecharts (you will get the same detail on the garmin gps with bluecharts)
