Cold Boiling Lake to Bumpass Hell Hike in Lassen Volcanic National Park: Wildflowers, Butterflies, and Hydrothermal Wonders

Lassen Volcanic National Park is one of the lesser-visited national parks in California, yet it is by no means less beautiful or interesting.

Boiling mud pots and other hydrothermal features, hikeable cinder cone volcanoes, the majestic Lassen Peak towering above the scenery, turquoise lakes, and countless wildflowers in the summer—all these wonders make the park a fascinating place to explore. This remains true even after the destructive Dixie Fire burned through about two-thirds of the park in 2021.

In this article, I will share my experience and best tips for hiking from Cold Boiling Lake to Bumpass Hell, where one encounters the awe-inspiring scenery of wildflower meadows, tiny streams, and turquoise lakes, all leading to the largest hydrothermal area in Lassen Volcanic National Park.

Table of Contents

1. Cold Boiling Lake to Bumpass Hell: A Tale of Butterflies, Burned Trees and Hydrothermal Wonders

2. At A Glance: 2021 Dixie Fire

3. At A Glance: California Tortoisesshell

4. Know Before You Go

Cold Boiling Lake to Bumpass Hell: A Tale of Butterflies, Burned Trees and Hydrothermal Wonders

When we arrived at the Kings Creek parking lot on a Sunday morning, we were pleasantly surprised. The usual crowds that often come with popular hikes on perfect days had not appeared. Instead, there were only a handful of fellow hikers just starting their journey.

On this clear morning in early July, we were already awestruck by the beauty of the area around the parking lot. Lush meadows cut through by streams of water and bursting with flowers. A light breeze swirled around us, immersing us in the fresh summer air. Despite the pleasant temperature of the air, we could feel the relentlessness of the sun at these high elevations, prompting us to apply a generous amount of sunscreen before we headed to the trail. A sign greeted us, indicating that Bumpass Hell may or may not be accessible. It did not deter us, as we had been told at the visitor center the previous day that Bumpass Hell was indeed open and accessible, at least from that particular trail.

We made our way up a moderately inclined hill, where we encountered large meadows sprinkled with trees and carpets of lupine. Most lupines were still in bud form, with a few already blooming in magnificent shades of purple.

After the short incline, the trail continued mostly flat, and very soon, we arrived at the first hydrothermal feature of the hike. If this had been the sole goal of our hike, we might have been slightly underwhelmed by the sight of tiny bubbles emerging from the surface of the so-called Cold Boiling Lake. However, for us, it was a pleasant preview of what was to come and interesting to see nonetheless.

The lake has a contradictory name for a reason: While the bubbles resemble boiling water, the lake itself is not at boiling temperature. In fact, it is considered a "dying" hydrothermal area, where you can see the last remnants of such activity.

As we made our way around the lake, we encountered more visually intriguing features: many fire-red dragonflies swarmed around the lake, and what appeared to be Pink Mountain-Heather was just beginning to open its reddish buds, revealing its glowing pink flower tips.

After passing the shoreline of Cold Boiling Lake, the trail began to ascend gradually to higher ground. The lush meadows on the ridges above the lake continued to be home to a constantly changing variety of wildflowers in early July. Many trickles of water flowed across the trail, and in some places, the soil was so drenched that it became saturated. Where it was particularly wet, the greenery grew even lusher, with vegetation growing high along the sides of the trail, immersing hikers in the dripping grass stalks.

While this appeared to be paradise, there was—literally—another side to the scene. To the left, Crumbaugh Lake shone turquoise amid dense greenery. The intense colors stood out, not only because of their vibrancy but also because of the contrast with the black, eerie-looking stalks that punctuated the landscape. Charcoal-colored trunks towered into the sky, sandwiched between the blue sky and the lush forest floor. It was already evident on the way into the park, and became even clearer now: The destruction and devastation caused by the Dixie Fire, one of the largest wildfires in California history, had left a profound mark on this natural wonderland. Hundreds and thousands of trees stood bravely together in their dark robes, their needles long reduced to ashes.

The view from the mountain ridge towards Crumbaugh Lake reveals a lot of fire damage, yet also many beautiful wildflowers at this time of year.

At a Glance: 2021 Dixie Fire

Overview

• When visiting Lassen Volcanic National Park, it is unavoidable to encounter the devastation caused by the Dixie Fire.
• As of January 2026, the Dixie Fire is the largest single (non-complex) wildfire in California’s history.
• The fire burned a total of 963,309 acres across five counties: Butte, Plumas, Shasta, Lassen, and Tehama.

Impact on Lassen Volcanic National Park

• Approximately 73,240 acres burned within park boundaries, affecting about 70% of Lassen Volcanic National Park.
• The fire entered the park from the southeast near the Juniper Lake area, impacting some regions more severely than others.
• Popular areas such as Manzanita Lake were largely spared from severe damage.

Fire Behavior & Management

• Within Lassen Volcanic National Park, fire effects were generally more moderate compared to surrounding areas.
• Forest management practices, including prescribed burns and fuel reduction, helped slow the fire’s progression.
• These management efforts remain critical as climate change contributes to larger and more extreme wildfires.

Learn More

• Read more about the impacts of the Dixie Fire on Lassen Volcanic National Park, including a short video, here.

It certainly left a bitter taste to see all these burned trees and to ponder how long it would take for the forest to recover in an environment that would only become harsher over time. For the moment, however, the ash-gray trees were sometimes forced into the background, like a constantly playing melancholic tune overshadowed by the loud and cheerful music from a ghetto blaster. Small streams of water flowed in some places on the hillsides, and the immense variety of flowers covering the lush meadows was simply awe-inspiring.

While I had to restrain myself from photographing hundreds or thousands of flowers, there were other creatures likely even more inspired by their sweet beauty than I was.

Hundreds of orange-glowing butterflies swarmed the meadows. We had already seen them around Lake Helen, where they covered large areas of the beach along the lakeshore. And here they were again, flying from flower to flower on the mountain ridges. Sometimes they would sit on the flowers with their wings closed, making them look like a dried, brown leaf. While the upper side of their wings signaled their presence from a distance with their brilliant color, the underside of the wings had the opposite effect, blending perfectly with the brown shades of the forest and allowing them to remain incognito for a while.

A California Tortoiseshell butterfly feeds on nectar from one of the many flowers.

At a Glance: California Tortoiseshell

Identification

• Striking orange-brown wings marked with dark patterns that flash brightly in flight.
• A wingspan of about 2 inches makes this butterfly easy to spot during mass movements.
• The underside of the wings is mottled brown, allowing the butterfly to blend seamlessly into tree bark when at rest.

Population & Migration

• Frequently seen in Lassen Volcanic National Park, especially during migration years.
• Moves seasonally between foothill canyons and high-elevation forests of the Sierra Nevada, occasionally reaching the Cascade Range.
• While the timing of migration is fairly consistent, population size fluctuates dramatically and remains largely unpredictable.

Remarkable Events

• 2004: An extraordinary swarm—40 to 50 miles long and up to 15 miles wide—moved south along the Sierra Nevada.
• 2019: The most recent major population explosion and mass migration.

How to Help

• If you encounter a mass migration on the road, slow to 30 mph or less to reduce butterfly fatalities as thousands cross at once.

Watching the butterflies feed reminded me that it was already mid-morning while we made our way up the mountain without having had a real breakfast, besides some dried mangoes, which probably qualified more as candy than anything else. The relentless sun and the incline contributed to my stomach growing impatient. After a few more switchbacks, we finally found a shady spot to sit and enjoy our sandwiches so we could explore Bumpass Hell without rumbling stomachs. While we ate, we heard some familiar tock-tock noises and quickly spotted the source: a woodpecker was making its way around a tree, tirelessly hammering its beak into the bark.

As we continued our hike after the refreshing break, we soon started to smell the scent of rotten eggs lingering in the air. Trail navigation confirmed what the smell had already announced: Bumpass Hell, the largest hydrothermal area in Lassen Volcanic National Park, was close. One more curve, and a spectacular panorama opened up before us. All shades of color painted an awe-inspiring scene—sulphur yellow, fool’s gold (iron pyrite) grey, deep forest green, pale ice-blue to turquoise bodies of water, and white steam constantly rising from the ground in several areas into the cloudless sky.

While the view from the top was amazing, we wanted to see the features up close, so we descended to the boardwalk in the midst of this hydrothermal wonderland. One feature that definitely stood out was the so-called Big Boiler, which was venting large amounts of steam like a tea kettle left too long on the burner. We learned that it was also by far the hottest feature in this 16-acre area and among the hottest fumaroles in the world, with a temperature measured as high as 322°F (161°C).

Many signs on the boardwalk explained the natural facts of this area. One that we might have missed left us with one open question on the way back:

Why is this hydrothermal wonderland called Hell, and who (or what) is or was Bumpass?

The story goes like this: More than 150 years ago, in 1865, Kendall V. Bumpass was the first person of European descent to venture into the area now named after him. While walking off-trail, he fell through some thin crust and burned his foot. Thinking he had learned his lesson, he returned some time later and gave a newspaper reporter and possibly others a tour of the area. This visit ended even worse:

“Our guide [Mr. K.V. Bumpass,] after cautioning us to be careful where we stepped, that the surface was treacherous, suddenly concluded with Virgil that the “descent to Hell was easy” for stepping upon a slight inequality in the ground he broke through the crust and plunged his leg into the boiling mud beneath, which clinging to his limb burned him severely. If our guide had been a profane man I think he would have cursed a little; as it was, I think his silence was owing to his inability to do the subject justice...” —Editor, Red Bluff Independent, 1865

His leg was severely burned and had to be amputated. From Bumpass’s perspective, he certainly went through hell on earth with this experience.

While there is some controversy around the story, it carries some very real lessons whether it is a campfire tale or the truth:

Nature is powerful. Stay on designated trails, be humble, and never underestimate the landscape beneath your feet.

Bumpass Hell, as captured from a viewpoint above the boardwalk, including the Big Boiler, one of the hottest fumaroles in the world.

Know Before You Go

Trail Info

• Bumpass Hell via Cold Boiling Lake Trail (described above)
• 📍 Distance: 5 miles (8 km) round trip
• ⛰ Elevation Gain: 980 ft (300 m)
• 🚗 Starting Point: Kings Creek Parking Lot
• ⚠️ Difficulty: Moderate; 7,400–8,250 ft (2,255–2,515 m). Be cautious if sensitive to altitude.
• ℹ️ A steady uphill hike with varied terrain. Trail description and navigation on AllTrails.

Shorter Alternative

• Bumpass Hell Trail
• 📍 Distance: 2.7 miles (4.3 km) round trip
• ⛰ Elevation Gain: 433 ft (132 m)
• 🚗 Starting Point: Bumpass Hell Parking Lot near Lake Helen
• ⚠️ Shorter and less strenuous than Cold Boiling Lake Trail.
• ℹ️ The most direct route to Bumpass Hell. See trail details on AllTrails.

Combination Option

• Consider combining both trails to experience the Bumpass Hell area more fully.

Best Time to Visit & Seasonal Closures

• Snow and ice can persist through summer at high elevations, especially in shaded forest sections.
• Some trails stay closed until conditions are safe. When we hiked in mid-July 2024, Bumpass Hell Trail had just reopened that very day.
• Lassen Volcanic National Park Highway generally opens between May and July and closes between October and November, depending on snowfall.
• Always check current road and trail conditions on the National Park Service website.
• Check current fire conditions before visiting; roads or even the park may close during wildfire season.

Hydrothermal Area Safety

• Stay on established trails and boardwalks at all times.
• The ground may look solid but can be a thin crust concealing boiling, acidic water or mud.
• Touching even cool hydrothermal water or mud can cause severe burns.

High-Altitude Considerations

• Lower oxygen levels at high elevations can make hiking more strenuous.
• High altitude may aggravate preexisting medical conditions—pace yourself and know your limits.

Leave No Trace & Bear Safety

• Follow Leave No Trace principles to protect Lassen’s fragile landscape, wildlife, and hydrothermal areas.
• Pack out all trash, including biodegradable food scraps, which can take surprisingly long to decompose.
• Minimize noise, observe wildlife from a distance, and never feed animals or remove plants, rocks, or cultural artifacts.
• Black bears live throughout the park. Never leave food unattended, and store all food and scented items (including toiletries) in provided metal lockers. If no locker is available, keep items out of sight in your vehicle trunk.
• Bears that become habituated to human food may need to be euthanized—proper food storage protects both humans and wildlife.

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