Rotenburo

Rotenburo is the Japanese term for an outdoor hot spring bath. The word combines露天 (roten, open-air) and 風呂 (buro, bath), and it refers to baths that are exposed to the outside environment. Rotenburo are a prominent feature of onsen culture and can be found in ryokan inns, public bathhouses, and spa facilities throughout Japan. The water is typically geothermal and mineral-rich, sourced from nearby hot springs, and the surrounding scenery ranges from garden and forest to mountain vistas.

Outdoor baths are usually constructed from stone, wood, or concrete and may be set into natural rock formations or integrated with landscaped settings. The experience emphasizes interaction with nature, including air temperature, wind, and seasonal changes. Water temperatures vary by source and season but commonly range from the upper 30s to the low 40s Celsius; some baths are hotter or cooler depending on local springs and safety considerations.

Etiquette for rotenburo generally follows onsen norms. Most baths are used nude, with gender-segregated facilities in many cases, though some places offer mixed or private rotenburo. Bathers should rinse thoroughly before entering, avoid bringing towels into the water, and keep noise to a minimum. A small towel may be placed on the head or kept at the edge, but not used to wipe or soak in the bath. Policies on tattoos vary by facility.

Rotenburo are valued for their combination of mineral waters and outdoor scenery, offering a seasonal appeal that is especially popular in winter for steam and snowy views, but enjoyed year-round. Some facilities provide private rotenburo or family baths for guests seeking a more secluded experience.