Abstract: A closure device for slit openings of aquatic sport suits, in particular of suits made of chloroprene rubber, with zippers which close the slit opening arranged both on the outside and on the inside of the aquatic sport suit. Both halves of the zipper are secured along the slit opening in close proximity to the sides of the opening. Two mutually overlapping tabs which also overlap the slit opening may be arranged on the inside of the aquatic sport suit along both sides of the slit opening. At least one sealing device is provided between the zippers (4, 8) which are arranged on the outside (1) and the inside (5) of the aquatic sport suit (2). If necessary, the zipper (8) disposed on the inside (5) is attached to two strips (12, 13; 12′, 13′) which are disposed on the inside (5) of the aquatic sport suit (2) and extend lengthwise along the slit opening (3), with the zipper (8) closing an opening region (3′) formed between the two strips (12, 13; 12′, 13′).