The hot springs at Mount Batur are rich in minerals and said to heal rheumatism, muscle pain and stiffness, fatigue, and even to enhance fertility. Even if you don't have any such complaints, soaking in these pools and looking out over the lake is wonderfully relaxing. Your muscles will certainly thank you for stopping for a post Mount Batur trek or bicycle tour soak. These are public pools, so on public holidays they are usually extremely busy and not quite so relaxing as when they are less crowded. There is a simple restaurant with eating platforms by the pools, but you can also bring snacks and drinks with you.
Getting to the hot springs takes about two hours from Kuta in a car, so it's really a full day tour if you want to have time to relax, eat, and take in the beauty of Kintamani.