A guide device suitable for use in an offshore drilling installation having at least one drilling riser extending from a floating support to the guide device on the seabed. The guide device includes a guide pipe in a buried position, wherein the guide pipe has a front end resting horizontally on the seabed, a curved intermediate portion buried in the subsoil of the seabed at a radius of curvature preferably being greater than 500 m, and an inclined substantially linear rear portion at the rear end of the guide pipe buried in the subsoil of the seabed at a given angle of inclination lying in the range 50 to 60.