There are a few feet (or meters) of freshly fallen snow outside your door. If you try to walk to your car in just your tennis shoes or boots, your feet will sink through that snow to the ground, leaving you with wet feet and damp clothing. But then, if you were to strap on a pair of snowshoes, you could reach your car without a speck of snow on you. How is this possible?
In very simple terms, snowshoes work by having a larger surface area than the bottom of your boot or tennis shoe. That larger surface area means that you have more snow supporting your body weight from below when you wear a snow shoe than you'd have if you were just wearing a size nine shoe. That extra surface area also redistributes the weight coming down on the snow from above. In other words, snowshoes help you to maximize a measurement known as pounds per square inch, or PSI; in this case, the amount of pressure that your body weight puts on the snow. In a tennis shoe or boot, there's a lot of body weight distributed over just a few inches; on a snowshoe, the body weight is spread out over many more inches.
That's why one pair of snowshoes doesn't fit all -- heavier people, or people carrying larger packs of supplies, will need bigger snowshoes. Lighter people won't put as much pressure on the snow to start with, meaning they can use a smaller pair of snowshoes. The snow conditions also matter. Packed snow, as opposed to fresh-fallen, fluffy snow, can take more pressure than the new flakes, so a trek across a newly dusted field of snow may require different snowshoes than a walk on a path created by a snowmobile.
You may also need different types of snowshoes depending on the kind of activity you'll be doing. On the next page, we'll consider the many different uses of snowshoes.