The end of throwaway plastic has been announced by UN environment ministers meeting in Kenya.
They signed an agreement saying the flow of plastic into the ocean must be stopped.
Scientists welcomed the agreement. But, they were unhappy it had no firm targets or timetables.
Politicians say it shows governments, industry and the public that big change is needed.
Vidar Helgesen, Norway’s Environment Minister, is leading the UN team on plastic pollution.
He told BBC News: “We came here with the need for action. We are aiming for zero sea litter. So it’s a breakthrough for zero flow of plastic into the ocean.”
He said that this was only the start of action against plastic litter.
Li Lin from WWF International told BBC News: “Today we have seen quite good progress on sea litter and micro-plastics.
“We would like to see this agreement used by governments, business, NGOs and consumers as quickly as possible. Because this is urgent.”
But stopping plastic litter will need new technology and new attitudes from the public. Among the many pollution challenges facing humans, this is probably one of the hardest.