Are you in for a warm bath? If you do, then why don't you try dipping on Mambukal's Rotenbaru or Outdoor bath. There are many pools inside Mambukal's resort that you could take a swim. However, this outdoor bath is different. You couldn't take a swim there as freely you would like. In my case, I just took a dip and sit at a corner. I couldn't take the water since it's very hot. Hot that you couldn't stay in the water for too long. But if your staying there or having an overnight, its good to take a swim there especially in the early morning where the weather is a bit cold. Aside from this pool, you could also see many different attractions in Mambukal. It's really a great place if you want to get away with the city.
If you could zoom this pic, you could see the water is smoking hot.