on the surface of the sea 14 and an undersea installation 18 which is represented in broken lines rests on the bottom of the sea 10 a flexible tubular pipe 20 extends between the two the latter has going from the surface installation 16 towards the undersea installation 18 a surface end 22 which is connected to the surface installation 16 a floating portion 24 which extends between the bottom of the sea 10 and the surface of the sea 14 substantially parallel to the bottom of the sea and a contact portion 26 which ends in a bottom end 28 which will be described hereinafter with reference to fig2 the contact portion 26 has a contact zone 25 or point of contact with the bottom of the sea 10 the floating portion 24 is provided with a succession of undersea buoys 30 which alternate with heavy modules 32 and provide the floating portion 24 with undulations at least one series of buoys is necessary in order to impose undulation on the floating portion and provide it with an excess length however the number of these concavities their orientation and the arrangement of the assemblies of buoys and their dead weight can be variable and can easily be determined by persons skilled in the art according to different parameters such as the swell conditions or the configuration of the field in addition the heavy modules 32 which are situated in the contact portion 26 allow the pipe to.