Lava Hot Springs is a city along the Portneuf River in eastern Bannock County, Idaho, United States. It is part of the Pocatello, Idaho metropolitan area. The population was 358 at the 2020 census. Located in the mountainous valley of the Portneuf River on the old route of the Oregon Trail and California Trail, the city has become a popular resort location, noted for its numerous hot springs amenable to bathing and a turbulent inner tube run through part of the town.