Medium and low altitude AERIAL SHOTS of Rocky Mountain winter landscape including partly snow-covered rocky peaks and snow-covered coniferous trees, ending with shot of helicopter landing on snowy ground. Various MSs, MCSs and PANS of Rocky Mountains winter landscapes, including partly snow-covered rocky peaks and snow-covered coniferous trees. CS of icicles to ZOOM OUT on snow patch on side of mountain and TILT DOWN to entrance of cave. Various shots of group of cavers cross-country skiing, carrying backpacks, of them arriving at Castleguard Cave taking off skis and backpacks. FOLLOW SHOT of them entering, taken from the inside of the cave.