What is a Gusseted Tongue?
A gusseted tongue is the term used for a boot tongue that is sewn to the upper as high enough as the lace eyelets permit. It prevents falling dirt, sand, or other debris from entering the interior of the boot. It is a typical feature on boots that are used in dusty or sandy environments such as the hot weather deserts of the Persian Gulf.
This design feature is important for waterproof boots. This is because when your boot becomes submerged in 6 inches or more of standing water, a waterproofed boot will only be able to provide protection up to the level where water can physically enter the interior of the boot. A gusset allows for waterproofing protection up to where it joins to the upper. The boot pictured provides waterproof protection from standing water up to the point where the top of the gusset ends.