Wow. There a whole lot of posters here who clearly don't deal with our oceans on a regular basis. You pretty much take the cake though for cluelessness.... not that it's anything new for you.
This containers are an ecological nightmare. Many contain contaminents and many FLOAT. We're seeing the same problem on the oceans that NASA is seeing in space flight. There's so much crap floating on the oceans that ships are running into it on a very regular basis. Do a little research before spouting off next time (yeah, I know, for you it'd be like pigs flying). In fact, many don't ship back empty - they contain dangerous waste - electronics laden with heavy metals, batteries and the like.
But hey, we could just take BigNate's standpoint of 'who cares, the world's too big for us to effect'. The bald eagles and the fish that we've basically wiped out (ever wonder why you don't see orange roughy and cod on restaurant menus any more, and you're starting to see a lot of tilapia?) might tend to disagree.
I'm no environmentalist. I support drilling for oil, own a nice big truck, and occasionally don't even recycle. However the ignorance shown in many of the posts here is staggering.