This is pretty cool. One thing is that it seems to get confused by nearby (smallish?) bodies of water. Near my house there's two creeks, they meet sort of forming a D shape. The traced path jumps across a small land mass once or twice between the creeks. Ultimately the drop would have ended up in the Raritan Bay regardless (although tool says Atlantic Ocean, I guess that's just me being pedantic) as the two creeks merge right before the mouth. Still, pretty cool.