"Watch the water"

Could this be another option for proving that past drop?

Flotilla of saildrones deploy to Arctic and Pacific for earth science missions. Unmanned vehicles will beam back vital ocean and atmospheric data

http://www.noaa.gov/stories/flotilla-of-saildrones-deploy-to-artic-and-pacific-for-earth-science-missions

June 26, 2018

NOAA and Saildrone, Inc. will launch the first batch of 11 unmanned sailing vehicles this week as part of NOAA’s expanding use of the cutting-edge technology to advance fisheries, weather and climate science.