How long does plastic last in the ocean?
Plastic polymers are designed to be extremely long-lasting and to resist breaking down. Thus, plastic pollution persists in the environment essentially forever.
While items may break up into smaller pieces as a result of exposure to wind, waves, and UV, they do not "break down"(biodegrade). It is often said that, with the exception of plastics that have been incinerated (or sent into space), every plastic item ever made on Earth still exists here, whether that be in landfill, the oceans, or on the summit of Mount Everest.