Great Smoky Mountains National Park is a sanctuary where, in one of the few places in the eastern United States with relatively little human influence, animal populations can live, propagate, and die, plants flourish in untold numbers and often reach record size, gene pools remain remarkably diverse, some species are rare or endangered, and new species may yet be discovered. These mountains have also become a refuge for humans, benefiting people far beyond the simple pleasure of being in an unspoiled forest by providing clean water to nourish communities and a diversity of life that helps make the world so interesting. Many have called the Great Smokies a living laboratory that provides a standard for monitoring the health of the world's environment.