Styx Creek is in the Otago Region of New Zealand

New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

. It flows into the Taieri River

Taieri River

The Taieri River is the fourth-longest river in New Zealand and is located in Otago in the South Island. Rising in the Lammerlaw ranges, it initially flows north, then east around the Rock and Pillar range before turning southeast, reaching the sea 30 km south of Dunedin.The upper reaches meander...

 in the valley near Paerau

Paerau

Paerau is a small settlement in inland Otago in New Zealand's South Island. It is located in the upper valley of the Taieri River), at the foot of the Rock and Pillar Range...

, about 70 km northwest of Dunedin

Dunedin

Dunedin is the second-largest city in the South Island of New Zealand, and the principal city of the Otago Region. It is considered to be one of the four main urban centres of New Zealand for historic, cultural, and geographic reasons. Dunedin was the largest city by territorial land area until...

. It was given the name Styx because of its use as a natural moat around the Paerau Prison, a historic prison dating from Otago

Otago

Otago is a region of New Zealand in the south of the South Island. The region covers an area of approximately making it the country's second largest region. The population of Otago is...

's gold rush era. The prison was situated on an outcrop of flat land originally bordered on three sides by the river, and on the fourth by a sheer cliff face.