It is good to read about a spate of new eco-documentaries at this year’s Sundance film festival (“Underwater Treasure,” January 24, 2009), several of which are about the troubled oceans. And it is especially good to read that these documentaries are turning activist in line with Al Gore’s “An Inconvenient Truth” (2006), which has made a mint in the meanwhile. As the founder of the Sundance festival, Robert Redford, puts it: “Just explaining the problem isn’t enough. You have to show what people can do about the problem.” The devastation of our planet is gathering an ever more furious pace, and it is high time for the eco-activists to turn toward film as a medium. If someone can make some money in the bargain, so much the better for the new genre. Eco-documentaries are likely to have a negligible carbon footprint, anyway.