By Christian Stenner and Kathleen Graham

Castleguard Cave has been featured in speleological writings since modern exploration began with Dr. Derek Ford and his team in the late 1960s. At 21 km in known length, it is Canada’s longest. Although this length pales in comparison to many longer caves in the world, its alpine setting, unique formations, biology, and terminus underneath the Columbia Icefield combine for an extraordinary landmark. This presentation will cover highlights of the exploration history of Castleguard, the current exploration projects, and challenges.

One of the most challenging leads that may reveal a new system of passages is at Boon’s Sump. British diver Martin Groves conducted a series of dives using a closed-circuit rebreather, cracked the sump, and emerged into an ongoing, dry passage. Martin had returned in 2012 with plans to continue exploration in the passage beyond the sump. After over 40 years of relative stability, we found the ice crawl located a few hundred meters into the entrance frozen shut. Since then, the ice crawl has been an intermittent problem that has prevented a return.

After the massive cave rescue operation in Thailand, Richard Harris and Craig Challen, key members of the response, as well as New Zealand caver Tom Crisp, opted to take on the Boon’s Sump dive project. Additional leads and projects deep in the cave were also waiting for a return. Partnered with the Alberta Speleological Society, the Return to Castleguard took place over 2 weeks in March 2020, just before the country had started enacting drastic changes due to the crippling pandemic.


  1. Hi guys, I had to laugh! This is the first time I’ve heard of a chain saw being used in a cave. Though it wasn’t clear to me if the saw cleared enough ice to get though. If so, how long was the ice plug?
    Somewhere in the 60’s (I’m terrible with dates), I had the honor of giving Mike Boon a ride several 100 miles across western Canada, parallel to the US border. You’ve heard of climbing bums, those guys who have an intense drive to climb and will go anywhere to do it? Well, Mike was just the same, but it was an intense interest in caves. Rick Banning

  2. I’ve known a bunch of “cave bums” and was pretty much one myself from 1973 – 1980, but Mike Boon was the top one. He never ceased being one to his dying day. I remember how one time he told me he had a pet. I asked, “Cat, dog?” He said, “No, a lump on my thigh.” He showed me and I said, “You’d better have that looked at.” He said, “And chance losing my pet?”

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