There are many companies cleaning the oceans, such as the Ocean Cleanup. There is also a company which creates Sea Bins. These pull in any plastic and filter the water for micro-plastics. I read about these in a book and believe that they, if made more accessible, can have a positive impact on our oceans. It is hard to clean what is already in the oceans but we can clean what is in landfill. If the pollution in landfill is recycled or made into something such as jewellery (a company called 4Ocean does this) this can prevent it reaching the ocean. It is vital that pollution is decreased because if we continue like this, it is estimated that there will be more plastic than fish in the oceans by 2050.
There are many alternatives to plastic such as metal instead of plastic straws, beeswax instead of plastic clingfilm, liquid wool and wood, PHB Biocomposites and ECM BioFilm, it's just a matter of weather we're prepared as a global community to embrace this change.