Jigokudani or “Hell Valley” is a spectacular, appropriately named valley just above the town of Noboribetsu Onsen, which displays hot steam vents, sulfurous streams and other volcanic activity. It is a main source of Noboribetsu’s hot spring waters.

From the valley, there are attractive walking trails through the wooded hills above Noboribetsu. If you follow them for about 20 to 30 minutes, you will get to Oyunuma, a sulfurous pond with a surface temperature of 50 degrees Celsius and a smaller, even hotter, mud pond nearby.