Jon Siegel has added a photo to the pool:
This is one of my favorite onsen areas in Nagano, famous for it's "healing" hot spring water. It's a very relaxing spot, with an excellent coffee cafe where they roast their own beans and very special sake and wine shop.
Side note but sometimes I forget the insane amount of detail the D850 captures, even when using an old antique lens like the Nikkor 35mm f1.4 ai-s.






