watershedplus:

As a demotivation campaign against the FRAC guerilla, the Colombian Ministry of National Defense launched the Operación Ríos de Luz (Operation Rivers of Light) for Christmas 2011. They asked relatives and friends of people from the FARC to collect messages and gifts for Christmas. The army packed these accompanied by a message “Do not miss this Christmas. Demobilize” in floating illuminated balls and spread these on several rivers in the country.
Guerilla camps are positioned nearby rivers as they use them as important channels of communication and transportation.

(Earlier works created by artists used similar effect: from the Japanese tradition of floating lanterns to Installation of Floating Lights in Hudson River, New York 1980; River of light, Calgary, 2010; Light Drift, Philadelphia, 2010; The Wishing stars, Tokyo, 2012, etc.)

via PSFK