Pollution in the Water

What exactly does it mean to have pollution in the ocean? This literally means that piles of garbage and waste are building up and up. The oceans literally have huge piles miles high. And people are wondering why we cant just scoop up the pollution. The pollution has allowed animals to make homes and shelters. So that is why we can not scoop up the garbage. Most of the pollution is plastic. The earthquake in Japan has also lead to the build up for this pollution.