The title says [Tokai-Dairotenburo] which basically translates to" large open-air bath of Tokai." The hot spring itself is situated in Okuhida, a pristine region in Gifu prefecture known for its amazing all natural outdoor baths and spas.
For me, especially during spring, visiting these mammoth outdoor baths can be simply amazing. Winter season is good too, but you find that most of your very large baths like the ones you see in this post close during winter, so if you're planning a vacation than keep that in mind. Okuhida is one of many thermo-treasure troves and requires several trips to really take in the true Japan onsen experience of that region - it's my fourth time there.
These amazing [dai-rotens] are really nice when taking a break in between destinations. I really enjoy relaxing in, and soaking in the surrounding green and crisp clean air. What a pity so many people miss out on these very simple pleasures.
( all photos are watermarked)