Lower Indian Bathtub Hot Springs is a natural thermal spring in Idaho. Its water was recorded at about 108°F (42°C) at the surface — a hot water temperature. That figure is a historical maximum surface reading from the USGS thermal-springs inventory, not the temperature of a soaking pool, and it doesn't tell you whether the spring is developed, accessible, or safe to enter.
Hotter than the 104°F hot-tub limit that health agencies recommend — too hot for many people, with a real risk of overheating and burns. Test the water and keep exposure short, if you enter at all.
Because Lower Indian Bathtub Hot Springs's recorded temperature is above the level health agencies consider safe for soaking (about 104°F / 40°C), treat it as a hazard first. Water this hot can cause burns, and the recorded figure is the hottest point at the source — cooler mixing pools may or may not exist. Never assume a spring is safe to enter based on this classification alone.
This listing comes from the USGS/NOAA thermal-springs inventory (a reference dataset compiled from records dating to the 1960s–1980s). It does not include ownership, developed-vs-primitive status, or access rights. Many U.S. thermal springs sit on private, tribal, or protected land, or are undeveloped and unsafe — always verify legal access and current conditions with the land manager before visiting, and follow Leave No Trace.