Beppu is a hot-spring city of 113,045 people (November 2023) on the north-east coast of Kyushu, Japan, at the western end of Beppu Bay in Ōita Prefecture. Its 125 km² hold 2,909 hot-spring vents, more than a tenth of the 27,644 counted across Japan in a 2004 Ministry of the Environment survey, and they release more than 130,000 tonnes of hot water a day, the largest discharge in Japan and second in the world only to Yellowstone. The heat comes from young volcanoes behind the city, Mount Tsurumi (1,374.5 m) and Mount Yufu (1,583.3 m), and from faults that flank the alluvial fan the city is built on. The water is shared out among eight spring districts, the Beppu Hattō, and the seven "hells" (jigoku) kept for viewing rather than bathing. What changes most through the year is the rain, the look of the steam and the way the city uses its water.
December to February: Dry Months and White Steam over Kannawa
Winter is the dry season on this side of Kyushu. At the Japan Meteorological Agency station in neighbouring Ōita city, the 1991–2020 normals give just 47.1 mm of rain in December, 49.8 mm in January and 64.1 mm in February, and snow is almost unknown, averaging about 1 cm a year. Beppu’s own January mean is around 4.3 °C. In cold air, the steam that rises all year from vents and chimneys condenses into thicker white plumes against the hills.
Nowhere shows it better than Kannawa, where jets of white steam rise from springs between inns on narrow, winding streets. Kannawa’s water emerges at about 64 °C in summer but only about 60 °C in winter, and is cooled to around 45 °C in the soaking pools. Five of the seven hells of the Jigoku Meguri circuit are in Kannawa within walking distance of each other; the other two are in Shibaseki, a short drive away.
Shibaseki has its own winter draw: a hot steam bath beside a mountain stream, designated a national health onsen resort, where legend says Emperor Daigo bathed in 895. Among the Kannawa hells, Oniishibozu Jigoku is a set of ponds of boiling grey mud whose bubbles resemble the shaven heads of monks, and Kamado Jigoku, the "furnace hell", has a pond that changes colour with the temperature and the weather. The full circuit of seven takes about two to two and a half hours.
The fan and faults beneath the steam
The urban area sits on an alluvial fan and coastal plain about 5 km wide and 10 km long, built by the Asami, Haruki and Sakai rivers as they ran down from the mountains into the bay. Seismic faults flank the fan on its north and south sides, and they give rise to a large number of the city’s thermal vents. The bay itself is a tectonic basin at the southern end of the Median Tectonic Line, part of a five-million-year-old zone of crustal stretching in central Kyushu, and the city’s back is formed by Quaternary volcanoes. Tsurumi, a lava dome, still shows fumarole activity.
March to May: Spring Rain on Tsurumi and the April 2016 Earthquakes
Rainfall climbs steadily through spring, from 99.2 mm in March to 119.7 mm in April and 133.6 mm in May at Ōita. This is when the mountains behind the city start to recharge. Mount Tsurumi rises to 1,374.5 m within the city limits, and the Beppu Ropeway, opened in December 1962, links the city with the mountain. Mount Yufu, on the border with Yufu city, is a stratovolcano whose last eruption, about 2,200 years ago, collapsed part of the mountain. Higher still in the city’s western area, Shidaka Lake lies at 600 m, and parts of the hills fall within Aso Kujū National Park.
Spring 2016 also showed how active the ground beneath the springs is. On 16 April a magnitude 7.0 earthquake struck under Kumamoto city, the main shock of the Kumamoto earthquake sequence, and strong tremors reached as far east as Beppu. The quakes ran along the Beppu–Shimabara graben, a rift that crosses central Kyushu, and they interacted with the Beppu–Haneyama Fault Zone, where the active faults at the southern end of the Median Tectonic Line fork in two directions. In Ōita Prefecture three people were killed, ten houses collapsed and more than 8,000 were partly damaged. The springs, in other words, rise through a part of Kyushu that is still being pulled and broken.
Not all of Beppu’s landmarks are geothermal. On Mount Takasaki, where Beppu meets Ōita city and Yufu, more than 1,200 wild Japanese macaques live in troops that take turns visiting the Takasakiyama Natural Zoological Garden, opened in 1953 after the monkeys were drawn down from raiding farms with sweet potatoes.
June to August: Tsuyu Rain, Blood-Red Ponds and Fireworks on Beppu Bay
The rainy season, tsuyu, reaches Kyushu in early June and usually lasts until mid-July, as a stalled front sits over southern Japan. At Ōita, June is the wettest month of the year, with 313.6 mm, followed by July with 261.3 mm, and average humidity rises to 77%.
Two of the hells sit side by side in Shibaseki. Chinoike Jigoku, the "blood pond hell", takes its name from red hot mud coloured by iron oxide and is described as the oldest natural hell in Japan; it already appears, as Akayusen, in early writings of Bungo Province. Its iron-rich water is also piped to baths in Kamegawa. Next door, Tatsumaki Jigoku, the "tornado hell", is the only geyser of the seven. It erupts every 30 to 40 minutes, and without the roof built over it the jet would reach about 30 m.
When the front lifts, summer heat arrives. August is the hottest month, averaging about 26.2 °C in Beppu and 27.7 °C at Ōita. In late July the Beppu Fireworks Festival sends 5,000 fireworks up from boats floating on Beppu Bay, one of the largest displays in the prefecture. In Kannawa, Umi Jigoku, the "sea hell", keeps its cobalt-blue water at 98 °C, hot enough to boil onsen eggs. At Oniyama Jigoku, about 80 crocodiles live in water warmed by the springs, in what was Japan’s first crocodile breeding facility, and at Shiraike Jigoku the steam heats an aquarium of tropical fish such as pirarucu and piranha. On the shore, Beppu Kaihin Sunayu, where bathers were buried in spring-heated sand beside the sea, closed for redevelopment in April 2023, but sand baths continue at Hyotan Onsen, and foot baths are scattered across the city, including one at the Sea Hell.
September to November: Autumn Rain and the Long Memory of the Aquifer
Rain returns in September, with 255.2 mm at Ōita, almost as much as July; climate figures for Beppu itself, compiled by Climate-Data.org, make September the city’s wettest month, with about 1,663 mm falling in a year. After that the air dries quickly: 144.8 mm in October and just 72.9 mm in November.
People have drawn on that aquifer for centuries. Bungo Province records describe the springs, and tradition says Kamakura-period sanatoria at Beppu, Kannawa and Hamawaki treated samurai wounded fighting the Mongol invasions. Hot-spring tourism began in earnest with the opening of Takegawara Onsen in 1879, and drillers using techniques from Kazusa had completed more than 1,000 wells by the end of the Meiji period in 1912. Between about 1919 and 1955 heavy pumping for farming and salt-making drained old sources and lowered water temperatures. In 1957 a new hot-water layer was found 200 to 300 m down and brought into use, and from 1964 the use of hot springs for salt production was banned, although spring water still warms greenhouses and fish farms.
Transport shaped the spa as much as geology. Beppu Port opened on 30 May 1871 with connections to Osaka and other ports on the Seto Inland Sea, a ferry to Uwajima on Shikoku followed in 1885, Beppu Station opened on 16 July 1911, and a seaplane route to Osaka began in 1923. Hamawaki, named after its beach and regarded as the birthplace of Beppu Onsen, merged with Beppu in 1906, and in 1991 it gained Yutopia Hamawaki, a health complex modelled on the European Kurhaus. Beppu’s sister cities include Atami, another Japanese spa town, since 1966, Rotorua in New Zealand since 1987, and Bath in England since 1994.
Other uses are older and more local. In Myoban, on the hill facing Beppu Bay, mineral deposits are collected on blue clay inside thatched huts called yunohana-goya and dried into crystals sold as bath salts. In Kankaiji, rebuilt as a resort after a wildfire in 1931, spring heat also drives a large geothermal power plant. Visitors can also work through the onsen stamp rally across more than 150 bathing facilities, including 16 municipal bathhouses, in the eight districts named the Beppu Hattō in 1924, the same year Beppu became a city, and 88 stamps earn the title of onsen meijin, or onsen expert.
Wet or dry, Beppu’s 2,909 vents keep discharging through all four seasons. To compare Beppu with another volcanic spa city, read about Rotorua’s geothermal fields in New Zealand; for the volcano at the heart of the Kumamoto earthquake zone, see the Aso caldera; and the weather systems that bring tsuyu and autumn rain to the whole country are explained in our page on the climate of Japan.