Home/Nagasaki/Unzen/Obama Onsen — Longest Hot Spring Footbath in Japan

Obama Onsen — Longest Hot Spring Footbath in Japan

Published: Jul 22, 2026

Updated: Jul 22, 2026

Obama onsenlongest footbathcoastal onsensunsetfree

Obama Onsen — Longest Hot Spring Footbath in Japan

Obama Onsen is a coastal hot spring town facing the Tachibana Bay, known for having the highest water temperature of any onsen in Japan — the source emerges at 105°C, making it unsuitable for bathing without cooling. The town's solution: a 105-meter-long public footbath (Hottofutto 105) running along the waterfront, where the spring water is cooled to 42°C and visitors can soak their feet while watching sunset over the bay.

The footbath, opened in 2010, is free and accessible 24 hours. Benches line the entire length, and the water depth (30cm) allows comfortable soaking while seated. The length (105m) refers to the source water temperature (105°C) — a playful naming convention typical of Japanese onsen marketing.

Essential Information

Opening Hours

Hottofutto 105 footbath: open 24 hours | Obama Jigoku steam cooking facility: daylight hours (check on-site)

Closed: Open year-round

Entrance Fee

Footbath: free | Obama Jigoku steam cooking: ¥100 for 20 minutes | Towel: ¥200 at nearby shops if needed

Best Season

Year-round | April–September for sunset foot-soaking with bay views | Summer evenings for the most social atmosphere

Visit Duration

30–60 minutes (footbath) | 2–3 hours with jigoku cooking, waterfront stroll, and ryokan day-use onsen

Getting There

Access Information

Obama-cho, Unzen City. 30-minute bus from Isahaya Station. The footbath runs along Obama Marine Park waterfront. Free, open 24 hours. Bring towel (sold at nearby shops for ¥200 if forgotten).

Insider Guide

Premium

**Sunset timing:** The footbath faces west across Tachibana Bay toward the Shimabara Peninsula. Sunset from April to September sets directly over the water, and the foot-soaking position with sunset view creates an unusually relaxing combination. The benches fill by 18:00 in summer — arrive 30 minutes before sunset to claim a spot. **Steam cooking:** Adjacent to the footbath, a public steam cooking facility (Obama Jigoku) allows visitors to cook food in the 105°C steam vents — bring eggs, sweet potatoes, or small fish for the authentic jigoku cooking experience. ¥100 for 20-minute steam access. Local vendors sell raw ingredients specifically for this purpose. **Overnight ryokan:** Obama has 30+ ryokan using the same source water (cooled for bathing). The seafood quality in Obama's ryokan kaiseki dinners is exceptional — the town faces the Ariake Sea, one of Japan's richest fishing grounds. Budget ¥15,000–25,000 per person including dinner.

View on Google Maps