Abstract: Sitting bathtub constituted by a tub (10) provided with an opening (11) extending almost down to the bottom of the tub and a hatch (15) to close this opening. When closing the bathtub before having a bath the hatch (15) is placed on the inside of the bathtub and the hydrostatic forces of the water forces the hatch against the edges of the opening where a seal is provided on the hatch. The sides and in particular the side with the opening are inclined or sloped outwards from the bottom so that the hatch with its seal will rest by its own weight against the seal. In particular seal (16), hatch (15) and the side of the bathtub are so arranged that a good sealing effect is always certain at the bottom of the bathtub when the rising water and the resulting hydrostatic pressure enable the sealing effect to climb upwards even on a light and slightly flexible hatch. This in turn enables the hatch to be very light and easy to handle and it is thus no inconvenience to have a loose hatch.