The hot spring's steam is so powerful that it was once used to power the heating system for the entire crocodile enclosure complex.
The first crocodile at this facility, named 'Ichiro,' was imported from Thailand in the 1920s.
The water temperature at the source is high enough to boil an egg in minutes, though it is regulated for the crocodiles' safety.
Oniyama Jigoku remains one of the few places in Japan where you can observe a large collection of crocodiles kept in geothermally heated environments.
The facility occasionally features displays of taxidermied specimens of former large crocodiles that lived on-site.
Oniyama Jigoku, known as 'Monster Mountain Hell,' is one of the seven iconic hot springs that comprise Beppu's 'Hell Tour' circuit. It is uniquely distinguished by its large-scale crocodile breeding program, which utilizes the intense geothermal heat of the thermal waters. The facility houses approximately 70 crocodiles, including various species like Saltwater and Nile crocodiles, living in enclosures warmed by the steam. The hot spring water temperature reaches nearly 100 degrees Celsius, requiring a specialized cooling system to create a habitat suitable for the reptiles. The site was the first facility in Japan to utilize geothermal energy for crocodile farming, a practice established in 1923. Visitors can observe the crocodiles from elevated walkways positioned directly above the enclosures. The geothermal steam is a persistent feature, often enveloping the area and contributing to the site's distinct atmosphere. The site remains a core component of Beppu's historical thermal tourism culture.
The upper observation deck providing a panoramic view of the crocodile enclosure with the geothermal steam rising in the background.
Wear comfortable, slip-resistant footwear as the paths can become humid and slick from geothermal steam.
Visit during the scheduled crocodile feeding demonstrations to see the animals at their most active.
Carry a handkerchief or towel, as the high humidity from the thermal vents can be intense.
Do not mistake this for a standard zoo; it is a thermal spring site where reptiles are a secondary feature to the geothermal activity.
Maintain a quiet demeanor and do not attempt to touch or feed the crocodiles; respect all safety railings.
