New Zealand is located in Oceania, southeast of Australia. It consists of two main islands, named the North Island and the South Island, and a number of smaller ones in the South Pacific Ocean. The North and the South Islands are separated by Cook Strait. The Tasman Sea separates Australia from New Zealand. The landscape of the country is mainly mountainous, but there are also large sections of flat plains. The highest peak of the South Island is Mount Cook or Aoraki, while the tallest mountain of the North Island is Mount Raupehu that is an active volcano. The longest river of the country is Waikato that runs along the North Island. The extensive range of marine resources makes the country the seventh largest Economic Zone in the world.