M.J. H.
Yelp
Highly recommended for at least a full day or weekend--with time to also visit the natural thermal springs nearby, and the villages in Maremma. The Terme di Saturnia resort offers the thermal waters with spa facilities, treatments, and lodging.
We arrived at Terme di Saturnia in the late afternoon and were greeted by resort rep. Monika--who provided a necessary tour and helped coordinate our first visit: the resort is large and includes several thermal pools, spa, wellness club, golf course, and dining areas -- as well as accommodation for guests at the resort. In addition, and N.B.: For those not staying at the hotel, there is a different entrance for the pools (with locker room and showers) -- not the main entrance for the hotel and the Club Benessere (wellness club) -- and it's a short drive away, but not easy to find on the first visit. (If staying more than a few hours, the Club Benessere option is most convenient.)
We enjoyed soaking in the renowned Saturnia thermal waters, a spa treatment, and dinner at Acqualuce. Soaking in the water (especially the pool closest to the hotel reception and restaurant) was deeply relaxing; it must be noted that the smell of sulfur is very strong, but one does get used to it and it really felt wonderful and therapeutic.
The food and drink (fresh juices at the bar/lounge after the pool & spa, and birthday dinner at the restaurant) -- were very good, and the service was excellent. They prepared a delicious meal from Chef Bocci's menu, and the Miatre d' and staff, and our server Lorenzo made the evening extra special and memorable.