Tuscan Hot Springs
Hot Springs are high on the tourist "must do" list - and I can see why.

Saturnia
I must admit, I’d heard a few people say they were turned off by the strong sulphur smell and the little red worms that are in the Saturnia hot springs – so I didn’t have high hopes. But then, after driving an hour and a half out of our way, just to come and check it off our list – in the end, I’m glad I did.
As we turned yet another corner on the long, winding road that leads to Saturnia, all of a sudden, it popped out of nowhere - and it blew me away. Here, in the middle of nowhere, are these incredible natural hot springs that cascade down.
Yes, it smells. Yes, there are little red worms (and they’re harmless, so I’m told). But it was a pretty cool spot to park up and float in for the afternoon. The picture opportunities were also like nothing else. You can't go wrong when capturing the intensely blue water flowing down the layers of thermal baths.

TIP: the baths are free and open all year round. There’s metered parking a few hundred metres away that’s easy to assess. Make sure you put into your GPS Terme di Saturnia so you get to the right place, otherwise it will direct you into town.
Bagni San Filippo

This place surprised me. I’ll start with a disclaimer: there’s not much around. BUT, the natural hot springs here (in my opinion) were better than Saturnia - and here’s why.
1. They were a lot more expansive, which means you could walk a bit further and likely find your own little spot and waterfall that’s not infiltrated with tourists already.

2. There were no red worms (as far as I could tell) in these hot springs.
3. It was just so impressive. That white limestone that just crumbled beneath your toes and fingers when you touched it, was so cool. Highly recommend spending a morning or afternoon here.

TIP: We arrived around 10am and it was still pretty empty, but by the time we left, more and more people had arrived. If you want to secure a good position, arrive by 9am at the latest. The water temperature is beautiful, like a bath, so it’s perfect whatever time of year you visit.