A very short stroll up the hill along the road that leads to Wonosobo is Tuk Bimo Lukar, the site of an ancient spring and some old stonework, which transforms the muddy creek into a holy bath.
It's said that bathing in these icy spring waters preserves youthful looks and may even lead to eternal life. It's a relatively minor attraction in Dieng and is indeed skipped by almost all visitors due to its low-scale nature.
However, this is a good first stop on the inner Dieng circuit and prepares you for the increasingly impressive natural and cultural wonders. Entry is free and those wishing to bathe should do so with shoulders, mid-riffs and upper legs covered.