Korouoma is about 30 kilometres long, few hundred metres wide and up to 130 m deep canyon at Posio, Finland. The entire area is a natural reserve. At the bottom of the canyon there's Korojoki River, which ends up to Kemijoki River. There are plenty of species in varied nature of Korouoma. Some of species found are rare. Korouoma offers great opportunities for hiking, watching the nature, fishing and reviewing the cultural history of usage of nature at the area.