“Waterlicht” is a Dutch installation by Daan Roosegaarde that seeks to raise public awareness of rising sea levels.
It has been shown so far in places such as Amsterdam, London, New York, Paris, and Toronto. The net effect of the experience is specific to the site but Roosegaarde uses LEDs, lenses and humidity to make the magic happen.
A quick video:
These kind of installations — experiences, really, would seem to hold significant potential.