A sign north of where the road crosses the Gardner River marks the 45th parallel of latitude. 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", one of a very few spots in the park where visitors can soak in naturally-heated water. 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, the hot water runoff from the Mammoth Terraces, 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. It tends to be very crowded, so try to visit very early in the morning during peak season.