Tirta Gangga is the former royal water palace of Karangasem, a garden of pools, fountains, stone guardians, and stepping stones set among rice fields. It is one of East Bali's easiest pleasures: photogenic, compact, and genuinely restful if you arrive before the tour buses.
The pools are fed by spring water and still have a ceremonial importance, not just a decorative one. Bring a sarong if you plan to enter temple areas, and go early in the day for better light and fewer people. From Amed it is usually under an hour by road.