I booked this trip, because of the no other option except the Day trip in Santorino on March. The volcano place is ok, but not much things you can see. The Hot Springs is not really work. It was more likely swimming in the corner of the ocean. You can jump into the water from the boat and swim. That's it.
I felt mis guide with Hot Springs. If the hot weather season, the water temperature will be up, so that will might be fine.