O-gama is basically Nozawa's hot spring headquarters - if you've seen those iconic photos of steam rising from traditional buildings in Nozawa, chances are they were taken here. This spot is the real deal - it's where locals come to collect the super-hot spring water for cooking (we're talking hot enough to boil eggs and vegetables!).
While you can't bathe in O-gama itself (it's way too hot - around 90°C!), the area around it is photo central. You've got these lovely public foot baths where you can soak your feet while watching the steam rise, a beautiful little temple adding to the atmosphere, and several traditional public onsens nearby that are strictly for locals.