Boiling River

A sign north of where the road crosses the Gardner River marks the 45th parallel of latitude. The 45th parallel is an imaginary line that circles the globe halfway between the equator and the North Pole. This same line passes through Minneapolis-St. Paul, Ottawa, Bordeaux, Venice, Belgrade, and the northern tip of the Japanese islands. Contrary to popular belief, the majority of the Montana/Wyoming state line does not follow the 45th parallel through the park. A little distance south of the sign, a parking area on the east side of the road is used by bathers in the "Boiling River." Bathers must walk upstream about a half mile from the parking area to the place where the footpath reaches the river. This spot is also marked by large clouds of steam, especially in cold weather. Here, a large hot spring, known as Boiling River, enters the Gardner River. The hot and the cold water mix in pools along the river's edge. Bathers are allowed in the river during daylight hours only. Bathing suits are required, and no alcoholic beverages are allowed. Boiling River is closed in the springtime due to hazardous high water and often does not reopen until mid-summer.