Red shaded areas on ActiveCaptain charts

these red shaded areas show up in activecaptain, but not on my Garmin MFDs. What do the shaded areas mean?


  • Same question!  I have Navionics boating, too, and the exact same areas show up outlined with just a black dotted line.  In Navionics I can drill down to get more info but the black dotted lines areas are all just shown as 'Obstruction' which isn't very useful.