Another man was injured in the slide, which happened late Saturday afternoon on Mount Gerald west of Golden.
Police say the avalanche was triggered by the four snowmobilers high-marking -- seeing how high their machines could climb on the slope.
Another group of snowmobilers witnessed the slide and immediately began digging for survivors, but only one of the men was found alive.
The bodies of the three deceased were recovered by rescuers Sunday afternoon.
Avalanche conditions in the Hope Creek riding area, where the slide occurred, are not monitored by Parks Canada or the Canadian Avalanche Centre; instead, local tourism guides describe the area as unmaintained and for advanced sledders only.
The avalanche risk throughout the Interior is listed as 'considerable,' meaning backcountry travellers should carefully monitor the snowpack and avoid risky manoeuvers.
With files from the Canadian Press.