The endoscope has an alternating propulsion system to propel an endoscope shaft (1) into a channel-like cavity using an auxiliary unit (5) e.g. flexible tube with a fluid pad, or guided wire. The shaft and the auxiliary unit rest alternatively with respect to the cavity to be examined. The non-resting units are simultaneously propelled along the resting units into the cavity, where rigidity of the unit is larger than the shaft.
