That crazy mass of plastic may eventually be sorted out; I read that a teenager in India developed a cheap efficient way to turn billions of tonnes of waste plastic into a lot of money's worth of fuel (although I did also hear something similar about plastic bags a while ago).
I'm hoping it will make it worth someone's time to fish it out and do something with it.
And on a completely unrelated tip, I read that seawater actually contains trace amounts of gold, to the point where if you could find an efficient way to process it, you'd have access to billions of tonnes. Of course really, there's quite a lot of water, and there's the law of diminishing returns...