Shirahama Onsen

The JR Kuroshio limited express from Osaka follows the Kii Peninsula coast south for about two and a half hours, and when it pulls into Shirahama Station you step onto a platform with the Pacific Ocean visible at the end of the access road. Shirahama is a proper beach resort town, with the white sand of Shirara Beach pulling summer crowds and the cliff-top hotels that characterize mid-century Japanese coastal development lining the headland above it. Underneath that resort surface, though, is something considerably older. The Nihon Shoki, Japan's second oldest chronicle, records imperial visits to these springs in the seventh century. Shirahama sits alongside Arima and Dogo as one of Japan's three oldest recorded hot spring destinations.

The water is a sodium chloride and simple thermal type, clear and colorless in the bath, with a pH of 7.4 that makes it neutral and comfortable against the skin. Temperatures range from 32 to 70 degrees depending on the facility and the source draw. The salt content is high enough to leave a noticeable mineral residue on your skin after the bath, the kind that holds heat in for an hour afterward while you sit in a yukata looking at the sea. The water does not smell of sulfur and does not stain the tub. It is a functional, straightforward coastal spring.

The bath that demands attention is Saki-no-Yu, an outdoor facility set directly on the Pacific coastline at the southern tip of the Shirahama headland. The pools are carved into or built beside coastal rock, and the ocean sits a few meters beyond the outer wall. At high tide, waves push up against the stone and send spray across the bathing area. You can sit in 42-degree water while the Pacific rolls in underneath you, which is an experience that is difficult to replicate anywhere else in Japan. The original site dates back over a thousand years. Of the Yuzaki Nanayu, the seven ancient baths of the area, Saki-no-Yu is the only one remaining in its original coastal position.

Shirahama works well as a two-day trip. The first afternoon you swim at Shirara Beach and visit the famous sandstone rock arch at Sandanbeki cliff. The second morning, before the day visitors arrive from Osaka, you take the first entry at Saki-no-Yu and have the ocean bath largely to yourself. That sequence makes good use of what the place actually offers.