An open and exceptionally spacious observatory sauna with a sweeping view of the horizon over Ariake Sea. The blue sea and sky spreading out from the seating area are truly spectacular, giving you the extraordinary sensation of being steamed above the sea. With steady heat and a pleasant woody aroma, it is designed so you can enjoy luxurious sweating while watching the changing expressions of the sea over time.

A sauna on the Mountain Bath side that lets you feel as if you are wrapped in the lush green of the forest. Through the large glass windows, you can view Amakusa's nature through all four seasons, and warm your body thoroughly in a calm atmosphere. The quiet interior is also ideal for meditation, guiding both mind and body into deep relaxation while you feel the energy of nature.

A cold bath lavishly supplied with underground water nurtured by Amakusa's rich natural environment. With a maximum depth of 110 cm, it is deep enough for even adult men to immerse up to the shoulders and cool the entire body in a fully enveloping way. The soft yet crisp water quality unique to underground water feels excellent on the skin and gently firms up a body heated by the sauna.