Sulfur Banks, on the crater side of the road, is just one of hundreds of gas seep on the flanks of the summit crater spewing hydrogen sulfide, sulfur dioxide, carbon dioxide and steam. Hematite, native sulfur and gypsum minerals precipitate out of the gas flux streaming through the rocks, making colorful splashes on the outcrops. Children and people with heat or respiratory conditions, or anybody with a weak stomach should be wary of venturing down the road to see this.
Non-sulfurous steam vents, mostly across the road from the crater and at the aptly named Steaming Bluff, result from rainwater percolating down through the ground being boiled by the hot rock beneath and streaming up vents to the surface. There is a short walk to the Steaming Bluff from the Sulfur Banks parking area which comes to a breathtaking view of the crater and more productive steam vents.