Blowing bubbles the hard, messy way. The process works roughly as follows:
- Ground water seeps through cracks in the ground.
- 5-10 miles down, it comes in contact with magma (molten rock and volcanic gasses).
- The resulting high-pressure steam is forced back to the surface.
- In some places, the steam vents directly to the open air, releasing that characteristic sulfuric rotten-egg smell.
- Here you can see the steam bubbling up through standing pools of water, spilling over into shallow rivers of hot mud.