Plastic is everywhere - in food packaging, drink bottles and shopping bags, but what happens after we throw it away is causing a big problem for our seas.
It's thought more than five trillion pieces of plastic are in world's oceans.
Plastic takes at least 10 years to break down and is a risk to birds and animals like turtles, dolphins and whales.
The scientists warn the problem could double in the next 10 years unless people stop using so much plastic.
Watch Hayley's report to find out more...