This was once a hilltop thermal feature that would hurl mud into the nearby trees during eruptions, but a particularly large eruption blew apart the Mud Volcano, leaving a hot, bubbling mud pool at the base of the hill. Access to the area is via a short loop from the parking lot past the Dragon's Mouth and the Mud Volcano that is handicapped accessible, and a half-mile upper loop trail via Sour Lake and the Black Dragon's Caldron that is relatively steep. The rhythmic belching of steam and the flashing tongue of water give the Dragon's Mouth Spring its name, though its activity has decreased notably since December 1994. The Black Dragon's Caldron exploded onto the landscape in 1948, blowing trees out by their roots and covering the surrounding forest with mud. In January 1995, a new feature on the south bank of Mud Geyser became extremely active, covering an area of 20 by 8 feet and comprised of fumaroles, small pools, and frying-pan type features. The most dramatic features of the Mud Volcano area, including the huge seething mud pot known as the "Gumper", are open to the public only via off-boardwalk ranger-guided walks.