Optical cable having a central core with grooves along the outside, the grooves housing tubes containing optical fibers. The grooves are inclined to the core axis and preferably are sinusoidal in that they extend around the core in each direction while extending axially and do not complete a revolution around the core before changing direction. In preferred structures, the tubes contact around a concave base surface of the grooves or contact opposing groove walls. In addition, the tubes provide greater strength if they are in a load transmitting relationship with a metal sheath if there is one. The structure also allows for a different water blocking material to be used within the tubes than outside the tubes and within the grooves so as to satisfy different property requirements.