Key Findings: 1. Marine litter, including plastics and microplastics, has grown drastically and is projected to more than double by 2030. 2. Marine litter and plastics are a grave threat to all marine life and are influencing the climate. 3. Human health and well-being are also at risk. 4. The hidden costs of plastics for the global economy. 5. Marine litter and plastics are threat multipliers. 6. Half of marine litter and plastics comes from uncontrolled waste streams on land. 7. Movement and accumulation of litter and plastics occurs over decades. 8. Advances in technologies and growing citizen science activities are improving detection, but consistency of measurements remains a challenge. 9. Plastic recycling rates are less than 10 per cent and plastics-related greenhouse gas emissions are significant, but solutions are emerging. 10.Progress is being made at all levels, with a potential global instrument in sight.