The location is not too far away from Bandung, West Java. A volcanic hot spot is close enough to the surface and it warms the ground/surface water. The presence of volcanic deposit in the water is good for your skin. People do take bath either out in the open or in close steam baths. There is a pro photographer that offered taking pictures of people while bathing or playing near the water fall. I put him just outside the frame, including only the family that he photographed.