Mud Volcano thermal area is about 6 miles from Fishing Bridge area on the way to Canyon Village on Grand Loop Road.
About one mile of boardwalks for the whole tour
Bubbling mud pots and lakes of acid – the sights and sounds of this area are fascinating, but accompanied by the sulfur smell of rotten egg.
Dragon’s Mouth Spring
NPS info: An unknown park visitor named this feature around 1912, perhaps due to the water that frequently surged from the cave like the lashing of a dragon’s tongue. The rumbling sounds are caused by steam and other gasses exploding through the water, causing it to crash against the walls of the hidden caverns.
The little video will give you an idea of what it looks and sounds like without having to smell the sulphur fumes. This was my favorite stop on the tour – I really could imagine a dragon living inside here!
NPS info: In 1870, explorers stood in awe as Mud Volcano spewed mud into the treetops, shaking the ground with each eruption. Two years later it was a pool of bubbling, muddy water. Mud Volcano had blown itself apart!
NPS info: Frothing and fuming as heat and gas rise from Yellowstone’s magma chamber, this muddy pool churns and cooks. Shaken again and again by earthquakes, the temperature beneath it rises and falls, transforming Churning Caldron.
Bubble, Bubble, Toil and Trouble!
This was the first thermal area I visited, and it really is surreal to walk around seeing steaming earth and bubbling pools.
Not that I’d want to verify this myself, but the name comes from the sour taste of the acidic water. The unusual milky green color comes from the bacteria and algae in the water.