A well logging cable including an optical fiber and a pressure sealed enclosure surrounding the fiber. The enclosure is adapted to be able to be elongated to the maximum expected axial strain on the logging cable without permanent deformation. In one embodiment, the enclosure is a corrugated-wall tube surrounding the optical fiber. The tube contains toroidally shaped rings within the maximum diameter portions of the corrugations in the tube wall. The cable includes armor wires wound around the corrugated-wall tube. In the preferred embodiment, the tube is surrounded by an elastomeric jacket, and is filled with hydraulic oil or the like to prevent entry of wellbore fluids into the tube under hydrostatic pressure.