Abstract: The ski boot comprises a shell upon a sole. The shell comprises a back heel portion, a shell tip and a front portion rearwardly extending from the shell tip to approximately an instep region. The front portion also has a longitudinal slot to divide part of the front portion into two shell flaps. A rear flap is pivotably mounted to the heel portion and a cuff is pivotably mounted to the shell portion, both the rear flap and cuff being capable of forward and backward movement. Structure is provided for closing the cuff in separable connection with the rear flap such that the cuff and rear flap when closed define at least part of a tubular shaft for a skiers leg. An outer wall above and at the sides of the front portion of the shell forms at least one chamber substantially sealed toward the outer surface of the outer wall and defined by the front portion at the bottom. The length of the outer wall is changeable depending on the pivotal movement of the cuff.