The United States has two coasts that touch two oceans - the Atlantic Ocean and the Pacific Ocean. There are also two non-continental states - Alaska and Hawaii - that touch the Arctic Ocean and Pacific Ocean respectively. The longest rivers are the Missouri, Mississippi, Yukon, Rio Grande and Colorado Rivers. The Great Lakes contain 21% of the world's fresh water and are the largest group of freshwater lakes on Earth. Three major rivers converge in Pittsburgh: the Allegheny, Monongahela, and Ohio Rivers.