Abstract: Fin according to the invention, with a seat (4, 22, 43) into which the foot may be introduced and wherein the walls (5, 8, 25, 41) of the seat grasp the foot at least partially, leaving out at least one area of the heel and of the ankle. The action of taking off and wearing the fin is made easier by providing that the fin (1, 21, 42), after the introduction of the foot into the seat (4, 22, 43) is automatically held back on the foot and removably connected thereto. There is also provided a combination of a fin of the aforesaid type with a type of footwear, like a boot (2), a shoe, or similar. In this case, the easier wear is due to the fact that the fin (1, 21, 42) is automatically held back on the footwear, being removably connected thereto.