Water covers more than 70 percent of the planet's surface, making our rivers, lakes and oceans the lifeblood of our planet. Many of these bodies of water may be out of sight and out of mind, but our health may depend on their protection.

Currently, scientists believe the world's largest garbage dump isn't on land...it's in the Pacific Ocean. The Great Pacific Garbage Patch stretches from the coast of California to Japan, and it's estimated to be twice the size of Texas. "This is the most shocking thing I have seen," Oprah says.

In some places, the floating debris—estimated to be about 90 percent plastic—goes 90 feet deep. Elsewhere, there are six times more pieces of plastic than plankton, the main food source for many sea animals.

Where did this trash come from? Marine biologists estimate that about 80 percent of the litter is from land, either dumped directly into waterways or blown into rivers and streams from states as far away as Iowa.