Nanki-Katsuura Onsen (Nachikatsuura)

What to expect

Nachikatsuura is a fishing town on the southeast tip of the Kii Peninsula in Wakayama Prefecture, known for its tuna market and as the gateway to Nachi Falls and the Kumano Kodo pilgrimage routes. Its hot springs go by the name Nanki-Katsuura Onsen. The town tourism organization says the area has more than 200 sources, and they range from big seaside hotels on the bay to small bathhouses in the back streets and quiet mountain springs inland.

The famous one is Bokido, a natural sea cave at Hotel Urashima, on the headland across the bay from the harbour. Hot spring water rises inside the cave and collects in rock pools that look straight out at the Pacific through the cave mouth. You hear the waves and, from the right side at the right hour, watch the sun come up over the sea. The cave is about 25 m (82 ft) wide, 50 m (164 ft) deep and 15 m (49 ft) high. The hotel says the name, “the cave where you forget to go home”, was given by Tokugawa Yorinori, lord of the Kishu domain, after a visit.

Most visitors combine a soak at Bokido with something cheaper and more local, such as the small Hamayu public bath near the harbour.

Hotel Urashima’s baths

Hotel Urashima (1165-2 Katsuura, tel. 0735-52-1011) spreads across several buildings on the headland and has its own 10 sources, reaching about 122°F50°C. The water is a sulfur-bearing sodium-calcium chloride spring, weakly alkaline, and the hotel says its large baths are source-fed (gensen kakenagashi). It does not say whether any water is cooled, heated or chlorinated. The hotel has six bath areas:

• Bokido (main building): the large cave bath, 5:00 to 10:00 and 13:00 to 23:00, with men and women swapping sides between sessions.
• Genbudo (Nisshokan building): a second natural cave bath on the same source, 5:00 to 12:00 and 16:00 to 23:00. It was closed from April 1 to July 31, 2026 for the building’s renovation.
• Taki no Yu and Hamayu no Yu (main building): baths beside a natural rock face with the sound of a waterfall, swapping between men and women morning and evening.
• Iso no Yu (Nisshokan): a bath by the waves.
• Yoho no Yu (Sanjokan): a hilltop bath with views of the Nachi mountains, Katsuura Bay and the town.

Day visitors can use four of these areas, including both caves. The cleaning breaks matter: Bokido is closed 10:00 to 13:00, Genbudo 12:00 to 16:00, Hamayu no Yu and Taki no Yu 12:00 to 15:00, and Iso no Yu 9:00 to 12:00.

Typhoon note: because the caves open onto the sea, the hotel limits them in storms. For Typhoon No. 25 in September 2026 it closed Genbudo’s newest outdoor tub from September 18 and installed steel doors and timber beams at Bokido from September 19, leaving one tub on the women’s side and three on the men’s, with no sea view. The notice gave no reopening date. Check the hotel’s news page before you go.

The hotel is in the middle of a multi-year renovation. The Nisshokan building reopened on August 1, 2026, ahead of the hotel’s 70th anniversary in December 2026.

Other baths in town

• Hamayu (970 Katsuura, tel. 090-8847-7582): a small public bath with sulfur-bearing sodium-calcium chloride water from a 115°F46.3°C source, fed straight from the source and drained and refilled daily. ¥490 adults, ¥170 elementary school children, ¥100 younger children. Open 15:00 to 21:00, closed Sundays and Tuesdays; start times can change, so call. No soap or shampoo provided.
• Yurinoyama Onsen (tel. 0735-52-5106): a lukewarm, source-fed bath with hydrogen sulfide water, 10 minutes on foot from Yukawa Station. ¥400 adults, ¥220 children, 9:00 to 22:00, closed Tuesdays (open on holidays). About 20 free spaces.
• Kyukamura Nanki-Katsuura (Ukui, tel. 0735-54-0126): a hilltop outdoor bath with a sea view. ¥1,000 adults, ¥500 children 4 to elementary school, 11:00 to 19:30 (from 15:00 on Thursdays). Free shuttle from Kii-Katsuura and Ukui stations.
• Foot baths: Umi no Yu, the Tsukiji evacuation tower foot bath and Taki no Yu are free.

Nishiki no Yu next to Nachi Station and the Yatagarasu bath in Ichinono were both listed as closed in October 2026.

Getting there

• By train: from Shin-Osaka, the JR Limited Express Kuroshio reaches Kii-Katsuura in about 3 hours 40 minutes. From Tokyo, change at Nagoya for the Limited Express Nanki, about 4 hours in total.
• By air: fly to Nanki-Shirahama Airport, then take the limousine bus to Kii-Katsuura Station (about 1 hour 55 minutes), or a bus to Shirahama Station and the Kuroshio (about 1 hour 23 minutes).
• To Hotel Urashima: walk about 6 minutes from Kii-Katsuura Station to Kanko Sanbashi pier and take the Urashima-maru boat, about 5 minutes. In the day boats run about every 15 minutes; the last runs are about 18:30 from the hotel and 18:40 from the pier. A shuttle bus covers the route when the boat is not running.
• By car: park free at the hotel’s Aozora car park (Tenma 441, Nachikatsuura) and take the shuttle bus. The lot is open until 19:30.

When to go

The town is open all year. Avoid typhoon season (roughly August to October) if Bokido’s sea view is the point, or check the hotel’s notices the day before. Early afternoon on a weekday, just after Bokido reopens at 13:00, is a good time for day visitors. If you stay overnight, the morning session from 5:00 is when you can watch the sunrise from the cave.

Prices and booking

• Hotel Urashima day bathing: ¥2,500 adults, ¥1,250 children (3 to elementary school), towels included, no booking.
• Hamayu: ¥490 adults.
• Overnight at Hotel Urashima: booking line 0735-52-4111 (9:00 to 18:00). Children pay a facility fee from age 3.
• The hotel has planned closure days each month, listed on its news page.

Onsen etiquette

Wash at the taps before you get in, bathe naked, and keep small towels out of the water. Hotel Urashima asks bathers to remove rings and necklaces, because the sulfur water discolours metal. The hotel says bathing is not advised in early or late pregnancy. No tattoo policy is published at the hotel or the town baths, so ask before you pay.

Where to stay nearby

Hotel Urashima is the obvious choice for Bokido at dawn. The town has other seaside hotels and ryokan around the harbour, and Kyukamura Nanki-Katsuura in Ukui. Inland, the Kumano hot springs are an easy add-on: Yunomine Onsen with the tiny Tsuboyu, and the winter river bath at Kawayu Onsen. Shirahama Onsen is on the west coast of the peninsula.

Safety notes

• Waves: Bokido opens onto the sea. Stay back from the cave mouth in rough weather, and follow staff closures.
• Heat and sulfur: the water is hot and can tarnish jewellery. Keep soaks short and drink water.
• Floors: rock and tile floors in the caves are wet and uneven. Walk slowly.
• Last boats: the boat stops in the early evening; check how you will get back to the station if you stay late.