On this picture we can see a giant pot of paint that pours into this river, right in the middle of the city. But, why represent that ? The WWF want to show to the world that this pot of paint, isn't just a pot of paint. Because it pollutes millions litres of water if it's thrown in a river or if it isn't recycled.
So, this picture is a caricature of the reality intended to shock pepole. This picture denounce the pollution of water.
In my opinion, this caricature is great because the pot of paint is represented as giant, to show how much a simple pot of paint can pollute.