Ōyunuma (Great Hot Spring Pond)

Overview

Ōyunuma is a crater formed by a phreatic eruption of Mount Hiyoriyama (Hiyoriyama). This gourd-shaped pond, approximately 1km in circumference, features a vigorous outflow of approximately 130°C sulfurous hot springs from its depths, with the surface temperature reaching around 40°C-50°C and a grayish-black hue. Historically, sulfur deposits were harvested from the bottom. Ōyunuma is located a short 15-minute walk from Jigokudani (Hell Valley), easily accessible using the Jigokudani parking lot (free parking with a Jigokudani parking ticket). As its name suggests, Ōyunuma presents a truly hellish spectacle. The fantastical atmosphere of billowing steam and the pervasive scent of sulfur offers a unique and powerful experience unlike any other onsen. It's a place to feel the earth's energy and the immense power of nature. Be sure to visit when you're in Noboribetsu Onsen.