A steerable catheter (10) comprises portions (100, 105) of different stiffness, having a proximal end (11), a distal end, a lumen extending there between, at least one magnet (20) at the proximal end (11), at least a magnetic field to influence the proximal end (11), wherein portions (100, 105) of the steerable catheter (10) can be of different stiffness. The portions (100, 105) of different stiffness are in fact portions of variable stiffness based on a phase change between a liquid phase and a solid phase of a liquid-solid material in a at least partly double walled catheter providing a cavity for this liquid-solid material and having additional control elements configured to influence the phase of the liquid-solid material.