The reward for hiking the Bumpass Hell trail at Lassen Volcanic National Park is reaching Bumpass Hell. If you enjoy hydrothermal activity, you will definitely enjoy the mudpots and fumaroles that Bumpass Hell has to offer. As you come off the Bumpass Hell trail, you round a corner and get a grand view of the hydrothermal activity and a beautuful turqoise pool as your first glimpse of what is to come:
You also get the first whiffs of the sulfur “rotten-egg” smell that is so familiar with hydrothermal activity:
The lava rock that once filled this area has been eaten away and altered into clay by sulfuric acid. The acid can be linked to a high temperature form of sulfur (sulfur dioxide) released from the magma body that fires Bumpass Hell. The rotten-egg smell that fills the air can also be linked to sulfur. It is hydrogen sulfide gas, a forerunner to the formation of sulfur — yellow, pyramid-shaped crystals that form on the ground here.
From the first look at Bumpass Hell, it is a short walk down to the Bumpass Hell boardwalk which allows you to see all the different types of hydrothermal activity taking place at Bumpass Hell.