If you sailed the whole of Africa's 18, 950 mile coastline, you would visit 33 countries. Because the ocean has no boundaries, nothing can be done without consequences for the whole. The ocean can seem like a useful bin for the huge amount of waste produced by humankind, but this is not true. Pollution is building up, as oil, plastic and sewage are dumped from boats, cities and factories. On our blue planet, it can seem as though the bounty of the oceans is endless, but over-fishing and by-catch are also threatening marine resources.