Shima Onsen Katsuura Wakayama

Shima Onsen in Katsuura, Wakayama Prefecture, sits on the rugged Pacific-facing coast of the Kii Peninsula — a landscape of dark cliffs, deep river valleys and ancient pilgrimage routes that culminate in the sacred sites of Kumano. The coastline here falls within the Yoshino-Kumano National Park, and the surrounding cedar forests and sea-cut headlands give the onsen a setting of unusual natural grandeur.

The bicarbonate water emerges at 40 °C with an alkaline pH of 8.0, producing the silky, skin-softening sensation characteristic of this mineral type — an effect that bathers along this coast have appreciated for centuries, often after long days walking the Kumano Kodō pilgrimage trail. The combination of warm, mildly alkaline water and the sound of the Pacific below is a distinctly Kii Peninsula experience, rooted in a tradition of pilgrimage rest and coastal hospitality that has shaped this corner of Wakayama for over a thousand years.