
If you’re trying to find places in K-Country that are truly “hidden”, caves win. Often with only a tiny entrance, the caves of K-Country are readily missed from the outside, with their secret treasures hidden underground. K-Country has a reasonable number of caves, including the ice cave under Plateau Mountain and the ice cave on Moose Mountain.
A disclaimer
Caving can be dangerous. Caving requires skills and equipment similar to climbing. Never, ever consider caving without education on caving skills. On the bright side, Rat’s Nest is a cave in K-Country where you can do real caving even if you have not done it before.
About Rat’s Nest
Rat’s Nest is Canada’s 4th longest cave. It is inside Grotto Mountain just 10 minutes from Canmore. While it is a Provincial Historic Resource, it is not a “show cave”. There are no lights and no stairs. Just endless places to slither on your belly or squeeze through incredibly tight passageways with names like “The Laundry Chute” – or drop 20 m on a rappel, pictured at right. In Rat’s Nest, you’ll see what caving is really all about. Access to the cave is only via a guided tour with Canmore Cave Tours.
Why does K-Country have caves?
The best caves are in something called “karst” topography. Some rocks can be dissolved by water, and the result of that is called karsting. Limestone makes up a whole lot of the rock of the Rockies. Limestone is readily (if slowly) dissolved by water. The process also speeds up if the water is slightly acidic. Crack rock to let the water in, apply plenty of water over time, and you’ll end up with a karst feature like a sinkhole or a cave.
K-Country has a LOT of limestone. Courtesy of glaciation and snowfall, it also has a lot of water. As a result, you’ll find karst features all over K-Country, including limestone pavement and sinkholes.
How Rat’s Nest Formed

Rat’s Nest started forming about 55 million years ago along with the Rockies themselves. Faults in the then-forming Grotto Mountain started to let water in, and for 20 million years, the cave just got slowly bigger. Then along came the ice age, and from 1.6 million to 12,000 years ago, glacial meltwater had a heyday making the cave bigger. Then the glaciers receded, the cave drained, and for the last 10,000 years, water has slowly dripped through the cave leaving minerals behind.
What’s inside the cave?

A visit to Rat’s Nest will introduce you to spectacular cave formations, all as a result of the re-precipitation of minerals out of water, much the same way the same minerals form on your showerhead. Typical formations you’ll see include:
- Flowstone, a rock that looks like creamy liquid dribbling down a wall – except it’s rock;
- Soda straws, thin delicate hollow tubes that dangle from the ceiling pictured above, and grow a the rate of 1 mm per decade;
Helictites, like tiny soda straws that seem to ignore gravity and grow in curlicue shapes;
- Cave curtains, draping sections of calcite;
- Stalacties and stalagmites, when they connect form the classic pillars and columns;
- Moon milk, something like flowstone that is in fact not forming as a rock but has organic matter in it;
- Rimstone dams, looking like terraces of some miniature agriculture;
- A small pool, pictured below. All the water in the cave has to go somewhere, and it collects in a pool at the bottom of a large cavern.
And then there’s the “other stuff” you find in Rat’s Nest:
Overwintering harvesters (“Daddy Longlegs”, for the uninitiated), in little clumps);
- Bushy tailed woodrats, or pack rats, for which the cave is named. These are incredibly cute, looking like a cross between a pika and a chinchilla. There are numerous nests near the entrance. While fast and agile, they aren’t particularly afraid of people;
- Bones. For thousands of years, animals have entered the cave, fallen in and died. There are buffalo bones galore, plus sheep and deer and goats and all manner of canid bones. There are even fish bones, assumed to come from ospreys or other fishing birds leaving their carcasses behind.
A unique environment
Some of the things you see in Rat’s Nest are there because the cave is a constant 4° C and virtually 100% humidity all year round. As a result, harvesters and other bugs come in to winter. One thing you don’t see is bats. For various reasons, there are virtually no bats in the cave.Canmore Cave Tours offers two tours, an Explorer and an Adventure tour. Both go to similar places, but the Adventure Tour throws in the rappel and Laundry Chute tight slither, plus a few very tight squeezes. Both of these tours can be work, and are not for the out of shape. Expect bruises after your foray into the cave.
For more info on Rat’s Nest Cave, look for the book “Under Grotto Mountain: Rat’s Nest Cave” by the late Charles J. Yonge. If you want to learn more about caving in Alberta, you can contact the Alberta Speleological Society.
