The plastic waste epidemic.
It is estimated that 8 million tonnes of plastic waste per year flow into the world's oceans, the vast majority of which originates within 50km of the coastline.
80% of this waste comes from land based sources, mostly drink bottles, containers and soft plastics such as plastic bags. However, only a small proportion will float, the rest (94%) sinks to the ocean floor where it moves aroud on ocean current, breaking into smaller pieces, taking a very long time to breaking down completely.
Currently the estimates say the ocean floors contains an average of 70kg of plastic in each square kilometre!