Bordered by eight states and stretching across the middle of North America, the Great Lakes are five massive, blue jewels that hold over a fifth of the entire world's fresh water. But how did Huron, Ontario, Michigan, Erie, and Superior actually get there, and what makes their waters so vital to the continent? Follow the incredible journey of a single drop of water as it flows through this massive, interconnected ecosystem. From peaceful lakes to rushing rivers, over the thundering edge of Niagara Falls, and finally out into the vast Atlantic Ocean, this stunning exploration uncovers the dramatic life cycle of our continent's greatest natural resource. It is a fascinating look at the geological forces that shaped the lakes and a timely reminder of why we must protect this precious freshwater treasure for generations to come.