Bumpass Hell is the largest hydrothermal area in Lassen Volcanic National Park, and it announces itself with a smell. A mile and a half of trail from the road brings you to a bowl of steaming vents, boiling pools, hissing fumaroles and mud pots, all in shades of yellow, green and grey, with the sharp smell of sulphur rising in the air. The boardwalk threads through it at a respectful distance, and you can watch water bubbling and spitting only a few metres away, a reminder that the volcano is sleeping rather than dead.
The name comes from a man called Kendall Bumpass, an early guide and explorer who found the place in the 1860s and brought a newspaper man to see it. While showing off the area, he broke through the thin crust and plunged a leg into boiling water, an injury so severe that the leg later had to be amputated. The story is told on the trail with a wry sense of what can go wrong, and it explains why the boardwalk and warning signs are taken seriously. Stay on the marked path, because the crust here is thin and the water scalding.
Lassen Peak itself erupted between 1914 and 1917, the last major eruption in the Cascade Range before Mount St Helens in 1980, and the park preserves a landscape shaped by volcanoes. Bumpass Hell sits on the collapsed flank of an older volcano, Mount Tehama, and the hot springs are fed by heat still rising from deep below. Snow often lies on the trail into July, and the area is usually open only in the warmer months, so check before you plan.
The Lassen Park Road, which crosses the park, is a lovely ride: smooth, curving through forests of fir and hemlock, with views of lakes and peaks and a gradual climb to the high point of the route. It is closed by snow for much of the year, usually from November until late spring or early summer, and when it reopens, snowbanks stand higher than a rider on either side. Watch for wildlife and for cyclists, and expect cold mornings even in summer.
Chester, about thirty kilometres away, and Shingletown have petrol stations and basic supplies, and it is best to fill the tank before entering. Bring water, sun protection and a layer for the cold.
Allow two hours for the walk and take your time on the boardwalk. The place is better when you linger.