Trip Date: April 16, 2024
2024 GRAND COULEE ADVENTURE VACATION
Blue Lake Rhino Cave Exploration
Blue Lake / Jasper Inlet
Diceratherium Basalt Mold
Trip Report Summary
Region: Columbia Plateau (Washington)
Sub-Region: Lower Grand Coulee
Starting & Ending Point: Coulee Lodge Resort adjacent to Highway 17 on Blue Lake (Elev. 1100 feet)
Way Points: Jasper Inlet shore (boat ride); lower ledge & upper ledge & cave entrance (off-trail hike & rock scramble)
Approximate Stats: 2.0 miles traveled by boat; 0.2 miles traveled on foot; 275 feet gained & lost on foot; 3.0 hours elapsed.
Trip Overview
The Blue Lake Rhino Cave is a fascinating geological feature located in Washington’s Lower Grand Coulee, several miles downstream from Dry Falls. Incredibly, this cave represents the mold of a prehistoric rhinoceros that was engulfed in lava and subsequently decomposed, leaving a body-shaped void in the basalt bedrock. According to a HistoryLink article, it was discovered in 1935 by four rockhounds who were prowling around the cliffs above Blue Lake and found several bones inside. Paleontologists from Central Washington University and the University of California studied the bones, made full-scale models of the cave, and determined that the animal was a Diceratherium—a smaller ancestor of the modern-day rhinoceros. Geologists later estimated the lava flow to be approximately 14.5 million years ago.
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You would expect such a unique feature to be a major tourist attraction in Washington, but it seems to be a surprisingly well-kept secret. The main reason for this is probably the lack of easy access: the cave is situated in a steep cliff about 300 feet above Blue Lake. Because there are no roads leading to the cliff base, the approach involves either a cross-country hike around Blue Lake, an off-road drive down Jasper Canyon, or a boat ride into Jasper Inlet. Once you’ve gotten to the cliff base, the ascent begins with a loose scree-and-talus slope, followed by a somewhat exposed traverse along sloping ledges, and ends with a short but very steep climb up to the cave entrance. Although none of this is particularly difficult for an experienced hiker or scrambler, it does keep casual tourists away.
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I first heard about the Blue Lake Rhino Cave through one of the many science videos that we were shown in elementary school (they were called “film strips” back then). The year was around 1968 or 1969. Over the ensuing decades, I mentioned this cave to many people and received many skeptical looks or comments in return. The whole notion of a prehistoric rhinoceros being buried in lava and then being exposed by erosion seemed so far-fetched that even I started to doubt my memory! Thankfully, the internet came along a few decades later and not only verified that the cave actually does exist but provided me with a specific location.
Despite always having a strong desire to see the rhino cave in person, I didn’t make it happen until this year, when Fay invited Eileen and me to join her on a car-camping trip to Steamboat Rock State Park in Upper Grand Coulee. That was my golden opportunity. Neither Eileen nor Fay had ever heard about the cave until I mentioned it, but they were immediately on board with an exploratory trip.
Full Trip Report
Fay, Eileen, and I drove to Blue Lake on a chilly Tuesday morning with the hope of renting a rowboat to get us across the lake. Being mid-April, most of the lakeside resorts were still closed for the winter season. However, we found one—Coulee Lodge Resort—that was open early. I talked to the desk clerk and learned that they don’t have any rowboats but do have a couple motorboats for rent. When I explained that we just needed a boat to get over to the rhino cave, she offered me a special “early-season rhino-visit discount” of only $30 plus tax. I unhesitatingly blurted out something equivalent to “Giddy up!”
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The amiable resort owner, TJ, took me out to a pontoon boat to demonstrate its operation, and then he gave me some detailed directions for locating the rhino cave. I barely had a chance to thank him for this much-appreciated assistance before he offered to personally take us across the lake and pick us up later. Again, I blurted out something equivalent to “Giddy up!” and gladly accepted his generous offer. Eileen and Fay couldn’t believe our good fortune when I informed them that we now had a boat and a chauffeur!
With TJ at the helm, Eileen, Fay, and I took our seats on the pontoon boat and enjoyed a slow cruise across Blue Lake. Along the way, TJ told us that he had been a general contractor in Western Washington for many years before stumbling across Coulee Lodge Resort. The owner was a widow who needed help with maintenance. TJ took on the maintenance tasks and eventually bought the resort. It became clear to us that he loves his job and the entire Grand Coulee landscape.
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As we motored into Jasper Inlet at the mouth of Jasper Canyon, TJ pointed out some white paint marks on the high cliff directly above us. These marks consisted of several arrows, a letter “R,” and the word “RHINO.” You certainly don’t have to be a detective to determine where the cave is! He pulled up to shore and we all hopped out. To facilitate our pick-up arrangements, TJ handed me a walkie-talkie before heading back to the resort.
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Eileen, Fay, and I sat down on the grassy shore to eat lunch and scope out an ascent route. It appeared that our best option was to scramble up a scree-and-talus fan for about 150 feet to gain a lower ledge, then traverse rightward until able to work around the right-hand side of a lower cliff band, and then traverse leftward on an upper ledge. Both ledges seemed to have a pronounced downward slope, but we hoped that they were adequately wide for comfort.
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Our chosen route played out very nicely, and there was ample evidence that many other visitors have done the same thing. The steep scree was annoying as usual, but the down-sloping ledges are generally wide and well-trodden. Within 30 minutes, we found ourselves on a narrow dirt walkway directly below the rhino cave. Actually, there are two adjacent caves on a near-vertical face 10 feet above the narrow walkway.
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Although the climbing did not look difficult, the exposure prompted us to use a handline for safety. I tied into our 10-meter rope and scrambled up to the entrance by angling over from the right side. Peering into both openings, I could see that the right-hand cave is the rhino mold, whereas the left-hand cave appears to be a log mold. I was pleased to discover a tiny hole connecting both caves, such that I could thread a sling through it to create a bombproof anchor. A triple-length (180 cm) sling is perfectly sized for this purpose. With our safety rope in place, we all found that the 10-foot face directly beneath both caves is solid and straightforward.
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We all took turns squirming into the rhino cave and examining the interior details. We could identify the animal’s head at the far end, and three of its legs projecting to the right. Its fourth leg and hindquarters had been located at the eroded entrance. The surrounding rock consists of pillow basalt, which forms when lava flows into water. This indicates that the Diceratherium and adjacent log were lying in a pond or swamp at the time of burial.
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By the time all three of us finished our exploration, we could see TJ’s pontoon boat circling around Jasper Inlet far below. We packed up and hurried down to the pick-up spot. He excitedly asked about our experience, and we responded with big grins and six enthusiastic thumbs up!
While cruising back to the resort dock in mid-afternoon, I contemplated the fact that this trek was the culmination of a 55-year personal quest. The concept of a “bucket list” was completely unknown to me in elementary school, but now I can assuredly say that an exploration of the Blue Lake Rhino Cave was the first thing I ever put in my bucket!
Location Map
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Photo Gallery
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