The Sudd, is a vast swamp in southern Sudan, formed by the White Nile.
Its size is highly variable, averaging over 30,000 square kilometers. During the wet season it may extend to over 130,000 km².
The sunlight and water contribute to the proliferation of plants that have no roots and float on the surface, forming a sort of a live carpet. Eventually plants become larger, thicker which with time creates a dense floating plant life of the swamp. Apparently, it is so strong that it can hold the weight of large animals.
This photograph was taken by the National Geographic in November 2010: these are the Southern Sudan lost herds floating their "island camps" in the middle of the huge swamp.
The picture is clickable.