Official Mont-Tremblant gives you more information on the winter activities in Tremblant including what is a snowmobile.

A snowmobile, also known as Ski-Doo, skimobile or snow scooter,  is a one- or two-passenger motorized vehicle with one or two skis in front and an engine-driven single or double continuous track to propel it. It is designed to be operated on snow and ice and does not require a road or trail, but most are driven on open terrain or trails.  The snowmobile’s engine links to the track’s drive, which rotates on the ground creating a forward thrust. The wheels on a snowmobile are large gears with even spaced “teeth” that push forward in the snow with ease. Although they are heavy (up to 700 lbs), they glide with ease in the snow. Snowmobiles can accommodate up to two people comfortably, and can traverse the landscape of Mont Tremblant relatively quickly.