It only now occurs to me that somebody should have purchased thousands of rubber ducks[1], then traversed the 7th arc[2], tossing one* overboard every mile or so.
[1] https://en.wikipedia.org/wiki/Friendly_Floatees
[2] https://en.wikipedia.org/wiki/Analysis_of_Malaysia_Airlines_...
* Appropriately labeled with GPS coordinates of release, of course.