A self propelling catheter introducer system for exploring a body cavity is disclosed which includes a flexible tubular catheter, a propulsion section and a steering section located near the end of the catheter that is introduced in a body cavity. The propulsion section includes a flexible everting tube designed to push the catheter from inside the body cavity. The catheter can thus be made very flexible in bending, and a larger diameter catheter can be used without discomfort to the patient.