We can only take out large chunks at the surface. The small stuff goes into the animals and into river and seabed floors. We have a lot of water on this planet. There are bacteria that can break it down but this highlights the issue of plastic recycling. Ideonella sakaiensis can degrade PET and use it as energy but it converts it into carbon dioxide. Then there are a huge array of other plastics.

Taking even a reliably large clean part of plastic and making it back into plastic, when you know the exact material it is (called regrade in plastic moulding terms) degrades the properties. You would normally mix a small percentage of it in with virgin material. But over use means the moulding won’t work. That’s why you see a lot of it used in simple extrusions like decking.

We have too much plastic. We need to reduce its use to important components. Most sea plastic from land sources come from 5 main rivers. Mainly in Asia. So we need to stop throwing it in the sea while we’re at it. That largest contributor to sea plastics is from boats. One easy way to help reduce sea plastic is strangely to not eat fish.