The present invention relates to an impermeable shoe (1), particularly a hiking shoe, comprising a shank (2), a breathable membrane (3) and an inner liner (4). Said shoe (1) characteristically comprises a layer (5) of open-cell foam having a thickness of at least 5 mm, capable of forming a vertical ventilation space and extending exclusively on either side of the rear and interior of the shoe, intended to enclose the hindfoot area (6) over its entire height.; An object of the present invention is also a walking ensemble comprising a shoe (1), particularly a hiking shoe, and at least one removable part (5) which has a layer of open-cell foam having a thickness of more than 5 mm, capable of forming a vertical ventilation space, intended to be added by the user inside the shoe so that it extends exclusively on either side of the rear part enclosing the hindfoot area (6) over its entire height.