Some marine debris, like food waste or paper, are able to degrade (break down chemically) and disappear within a short period of time.
||Marine Debris Biodegradable Timeline
Other debris, like glass bottles, tin cans, and fishing lines, take a very long time to break down and can take several hundred years to degrade.
Many plastic debris that are created using human-engineered materials like nylon, polyethylene, and polypropylene, take an especially long time and may not even degrade completely.
Without being able to degrade, they may stay in the ocean forever, unless they are removed by people or marine animals.
Take a look at the chart below to see roughly how long it takes for different items to biodrade.