National parks are large of areas of public land . They give a safe home for local plants and animal . They help keep the air and water clean . They also give us the best trips . Today ,there are nearly 7,000 national parks around  the world . Forbes has listed 12 of the most beautiful ones in the world that will surprise  you with their  amazing landscape ,geographic wonders and colorful plants and animals . The Grand Canyon National Park of the US is one of the Seven Natural Wonders of the World . It is best known for its size and depth . It is 446 kilometers long ,up to 29 kilometers wide ,and 1. 6 kilometers deep . The _ of the canyon makes people think big . Every year ,about 5million people visit here . Taking a tour in the South Rim offers vistors the park's full views,while the North Rim shows beautiful wild flowers . If you love animals ,you'll like the Serrengeti Natinoal Park in Tanzania . The "Big Five "live here . They are the lion . African elephant ,African leopard ,black rhinoce and African buffalo . The name  "Big Five "came from the five animals that were the hardest to catch . Now they are what people most want to see in the wild . If you visit the park ,you should never miss the migration of over 1. 5million wildebeests and 250,000 zebras every year. This is the most famous site of the park . _  kinds of animals are mentioned in the passage.
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