Abstract: The present invention relates to a method and to a device for providing a closed chamber for the enclosure of optical fibre and/or optical fibre ribbon splices to a spliced underwater optical fibre cable. By providing the chamber (8) with at least one closable cover element, such as a cover plate (13), the chamber can be closed by means of said cover plate, subsequent to having inserted the ends of the optical fibre cables into said chamber and having spliced the optical fibres/optical fibre ribbons to said optical fibre cables. Oil can be delivered to the chamber closed by said cover plate, through at least one closable opening (14), resulting in a gas-tight and oil-filled chamber that provides reliable protection to the splices.