Another good writeup of why it's not "visible from space, for pete's sake! twice the size of Texas! Gimme a break" [/skeptic]
The plastic shit that can kill the critters is on the scale of a dime, say. And it is as deep as 50 or 100 feet. It's not like a mound of trash at the local landfill dense and high and dry enough to walk on. It's big. It's sparse. It's there. It's crap. And it's preventable, since the bulk of it came from land anyway.