A drill rod (10) for a drilling rig (1) comprises a tube (19) comprising at least one corrugated cut (20) extending through a wall of the tube (19) in a transverse (G) direction. Each corrugated cut (20) has a substantially spiral baseline (21) and is arranged to deviate from its baseline on both sides of the baseline forming a cut of a substantially corrugated shape spiralling along the tube (19). Such tube (19) is flexible enabling bending in a transverse direction (G) of the drill rod (10) and rigid to enable transmitting torque and thrust in a lengthwise (E), transverse (G) and rotational (H) direction of the drill rod (10) when rotated for drilling.
