Nigerian environmentalist Wonne Afronolly is working hard to clean up her city Port Harcourt.
Researchers say that 10 rivers are responsible for depositing 90% of the plastic pollution that ends up in the sea.
One of these is the River Niger, and Port Harcourt sits at its mouth.
Ms Afronelly told BBC Minute that the mindset of the people is her major challenge.
Video journalist: Dan Ikpoyi