One of the largest biological organisms in the world, the Great Barrier Reef is visible from outer space... but it might not be for long. Other than the sporadic oil spills which severely damage the reef, Australia's popular tourist destination is being affected daily by pollution, resulting in declining water quality. Littering tourists and excessive fishing are to blame for the reef's decline but 90% of the pollution is due to ‘farm run-off'. Farm run-off is when contaminated soil is flooded from rain and flows over the land into nearby rivers. Vast tracts of the reef have been polluted and without the proper care, future generations will be left with little to see of the once-thriving reef.