Pick one category for the following text. The options are - company, educational institution, artist, athlete, office holder, mean of transportation, building, natural place, village, animal, plant, album, film or written work. River Styx (Marquette County Michigan) -  The River Styx is a 0.6-mile-long (1.0 km) stream in Marquette County Michigan in the United States. It flows from the outlet of Ives Lake north over a waterfall to Third Lake an arm of Pine Lake. Via the Pine River (the outlet of Pine Lake) water from the River Styx flows to Lake Superior.
The answer to this question is:
Natural Place