Choei; Ni no Maru Onsen

Insider tip — Choei and Ni no Maru Onsen sit at Japan's southernmost peninsula tip in Kushimoto, Wakayama, where volcanic hydrothermal activity along the Nankai Trough boundary produces sulfurous springs close to sea level. The characteristic pale-blue tinted waters contain high hydrogen sulfide concentrations beneficial for skin and respiratory conditions. The surrounding Shionomisaki headland is a UNESCO Biosphere Reserve and the onsen sits within walking distance of dramatic Pacific sea cliffs. Summer visitors often combine a dip in the sulfurous baths with snorkelling in the coral-rich waters just offshore.