Jigokudani or Hell Valley is a sulphur-spewing valley just above the Noboribetsu Onsen Town. There are trails going up the woods to Oyunuma Sulfuric Pond (it says the water surface heats up to 50°C) which unfortunately was closed due to snow when we visited. The Onsens here have the strongest sulphur smell out of all other onsens we have visited. It even stays with me until I got back from Japan 😅 📸: @lanosian . . . .