GRAND CANYON, ARIZONA
Redwall Cavern: Grand Canyon's Largest River-Cut Cave
At Mile 33 on the Colorado River, a massive opening appears at the base of the Redwall Limestone. Carved by the Colorado River into 340-million-year-old limestone, Redwall Cavern is the largest river-cut cave in Grand Canyon. Its sandy floor stretches deep into the cliff, while the ceiling rises high overhead. People standing inside look surprisingly small.
When Major John Wesley Powell camped here in August 1869, he famously wrote that the cavern could seat 50,000 people. After walking inside, most visitors understand exactly why he wrote that.
You can reach Redwall Cavern only by rafting. Western River's
6-Day and
7-Day Grand Canyon expeditions stop here on the second day, giving guests time to wander the immense chamber, listen to the echoes, and stand inside one of the most unexpected places in the canyon.
What it's Like Inside Redwall Cavern
Most people stop talking for a moment after walking through the opening. The scale is difficult to process. Voices echo across the chamber and return from somewhere overhead.
Then the guides pull out Frisbees and footballs.
What looks from the river like a geological feature becomes a giant natural playground. Within minutes, people are throwing discs, exploring the edges of the cavern, or simply sitting in the sand taking it all in.
When it's time to leave, most people take one last look back through the opening. The cavern has a way of permanently recalibrating your sense of scale in the Grand Canyon.
How You Reach Redwall Cavern
Redwall Cavern is one of those places that exists exclusively for river runners. There is no trail to it. No overlook. No roadside turnout. You reach it the same way Powell did in 1869: by floating down the Colorado River and stepping onto the sand.
The Red Wall Isn't Actually Red
The towering cliffs above Redwall Cavern are composed of the Redwall Limestone, a rock layer formed about 340 million years ago when a shallow tropical sea covered this part of North America. Despite its name, the limestone is not actually red. Freshly broken rock is pale gray. The familiar red color comes from iron-rich layers higher in the canyon. Over millions of years, rainwater carried iron oxide down the cliffs, staining the limestone and creating the massive rust-colored wall seen today. Look closely, and you can still find fossils preserved in the rock. Crinoids, corals, and other marine life reveal that this section of Grand Canyon once sat beneath a warm inland sea.
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John Wesley Powell Slept Here
In August 1869, Major John Wesley Powell and his nine-man expedition camped at Redwall Cavern during the first recorded boat journey through the Grand Canyon.
At the time, much of the canyon remained unmapped and largely unknown to the outside world. Powell's expedition spent three months navigating rapids, scouting routes, repairing damaged boats, and documenting a landscape few Americans had ever seen.
Redwall Cavern offered something rare on the Colorado River: a broad sandy campsite sheltered beneath a towering stone arch. More than 150 years later, river runners still stop here for many of the same reasons.
Powell would later name the Redwall Limestone, the rock formation that surrounds the cavern today. His journals helped introduce the Grand Canyon to the wider world and remain one of the most important firsthand accounts of the river ever written.
Redwall Cavern: Frequently Asked Questions
Where is Redwall Cavern in the Grand Canyon?
Redwall Cavern is at mile 33 on the Colorado River, in the Marble Canyon section of Grand Canyon. That places it early on the upper-canyon river itinerary, roughly 30 river miles downstream of Lees Ferry, the put-in for long Grand Canyon trips. The cavern is carved into the base of the Redwall Limestone cliff on the right bank of the river, and it is not visible or accessible from either rim. The only practical access is by river.
How big is Redwall Cavern?
Redwall Cavern is approximately 300 feet wide, 150 feet from the opening to the back wall, and about 100 feet high at the top of the vault. Those are the real dimensions. Major Powell, who camped at the cavern with his 1869 expedition, wrote that it could seat 50,000 people. Once you are standing inside, you might really begin to wonder if Powell may have been right about that crowd size!
How was Redwall Cavern formed?
Redwall Cavern is a river-cut cave, carved into the base of the Redwall Limestone by the Colorado River itself. The limestone is a Mississippian marine deposit about 340 million years old, running roughly 500 feet thick through Marble Canyon. Over hundreds of thousands of years of high-water events, the Colorado scoured out a vast half-dome alcove by combining hydraulic pressure, abrasion from sediment and debris carried in the current, and the natural solubility of limestone in slightly acidic river water. The result is a shelter carved on a geological scale, not a dissolution cave like those formed by groundwater percolation.
Can you camp inside Redwall Cavern?
No. Overnight camping is not permitted inside Redwall Cavern, and lunch stops are not held there either. The National Park Service treats the cavern as a day-use site only, to preserve its archaeological integrity, protect the sand floor, and manage the volume of river traffic that passes the site through the commercial rafting season. Western River's 6-Day and 7-Day Grand Canyon itineraries make a short day stop of about an hour inside the cavern and then continue downstream to camp at a nearby beach.
How do you get to Redwall Cavern?
The only practical way in is by rafting. No maintained trail reaches the cavern from either rim, and the Redwall Limestone cliffs above the river make any descent technical and permit-intensive. On a guided rafting trip, the cavern is a short flat walk off the boat onto a sand beach, then across firm sand into the cavern mouth. No scramble, no climb. Guests in flip-flops or sandals make the walk, and so do children. On a Western River's 6-Day Grand Canyon Rafting Trip and 7-Day trip, the Redwall stop is built into the itinerary.
Which Western River trips visit Redwall Cavern?
Redwall Cavern is on the itinerary for Western River Expeditions 6-Day and 7-Day Grand Canyon rafting trips. Both launch at Lees Ferry and run the full upper two-thirds of Grand Canyon. The 3-Day and 4-Day River & Ranch trips launch at Whitmore Wash (mile 188), about 155 miles downstream of Redwall at mile 33, and they do not reach the cavern. Only the 6-Day and 7-Day trips make the Redwall stop.
Still curious to learn more?
See more common questions or contact us.
Experience Redwall Cavern on a Western River Guided Trip
Redwall Cavern sits at mile 33, early in the upper-canyon section and reached on the second river day of Western's longer Grand Canyon expeditions. Both trips launch at Lees Ferry and continue all the way through the upper two-thirds of the canyon.
Seven days exploring 188 miles of the Grand Canyon. Run famous rapids, hike hidden side canyons, camp beneath the stars, and helicopter out of the canyon.
- Begins: Las Vegas
- Best for: Extended Vacation
- Rapids: 60+ Class III-V
- Ages: 12+
Six days in the Grand Canyon. Run Crystal Rapid and Lava Falls, hike hidden side canyons, sleep on beaches no road will ever reach, and helicopter out of the canyon.
- Begins: Las Vegas
- Best for: Rapids & Hiking
- Rapids: 60+ Class III-V
- Ages: 12+
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