I don't think I've seen this type of Active Track video so I thought I'd share.  Nothing fancy, just raw footage out of the Mavic.  But it worked quite well with the little boat once I had it locked on.  I was still messing with the orbit controls and the altitude but everything else was smooth tracking.  I'm thinking that the nice, flat water created nice contrast to the boat which also allowed the Mavic to follow along.
Oh, at the end, I just flew it out over the lake to show my buddy how RTH worked.
One other thing I'll mention, it actually shows a boat icon while tracking.  I don't remember seeing this in the manual so I found it interesting at least.

Very cool man,

Works pretty well.