The Tapovan sulfurous hot springs in the Dhauliganga valley (India)
The small geysers of bubbling scalding water are pretty cool.
The hot water is captured and piped to a few pools and showers downhill below the roadside, but that's not a great place for a hot bath, since the pools are indoor and in poor conditions.
This is upstream from Joshimath, in the valley of one of the headstreams of the Ganges river.