In 2008, the Independent reported on the Great Pacific Garbage Patch. This is a mass of plastic floating in the Pacific Ocean, located between the US and Japan. In 2008 this was estimated to be twice the size of the US continent and still growing at an alarming rate as we continue to dispose of plastic wastes.

Wikipedia indicates that it is thought that 80% comes from land wastes (presumably coastal landfills and from rivers) and 20% from boats.

The type of waste found ranges from toys, bags, shoes, abandoned fishing nets, bottles, containers, etc. Besides the obvious unsightliness of it, why should we care since we also dump this in the ground in landfills?

Plastic is a man-made substance that will photo-degrade in the oceans into smaller toxic polymer units. So big marine life can get entangled in our trash or eat our trash and die and smaller marine life and plankton will absorb it put it back into our food chain.  Some of these plastic nurdles attract other man-made chemicals such as pesticides, which again will enter our food chain via the aquatic life that ingests it.

So do we want to care about:
1. The unsightliness
2. It killing over a million seabirds and more than 100,000 marine life a year
3. The chemicals from plastic degradation being leached into our oceans and thus into the food chains directly or indirectly in products such as fertilisers.
4. For many of us around the world, it will be on our dinner plate whether served as a fish or camouflaged as fish fingers, or some other marine life.

If you do care then look at how you can reduce your usage of plastic. 

If you're from the US, you might consider joining this organisation: http://www.greatgarbagepatch.org/take-action/