The present invention relates to a device for controlling underwater pressure, which device is adapted for use in drilling installation comprising subsea blow-out preventer (1) and surface blow-out preventer (2) wherebetween a riser (3) is arranged for communication, and for the purpose of defining a device in which the use of choke line and kill line can be avoided, it is according to the invention suggested that the device comprises a high pressure riser (3) and a high pressure drilling pipe (14) which are so arranged between the subsea blow-out preventer (1) and the surface blow-out preventer (2) that they can be used two separate high pressure lines as a substitute for choke line and kill line.