A national park is a large piece of land in which animals are free to come and go. Trees and plants grow everywhere. People go to a national park to enjoy nature. Yellowstone is the USA's first and most famous national park. It became the world's first national park in 1872. It is also the world's largest park. The land is still unchanged. The valley of the Yellowstone river has coloured rocks and three large waterfalls. In the valley you can meet wild animals walking,resting and eating. Yellowstone Park is famous for its geysers. These holes in the grand shoot hot water into the air. There are about 70 geysers in the park. The most famous is Old Faithful. About every hour Old Faithful shoots hot water hundreds of feet into the air. Two and a half million people visit this beautiful park each year.