Our goal is to develop a navigation system for a mobile robot that mimics human navigation. To achieve this goal the robot has to perceive sufficient information about its environment to determine where there are safe paths to travel. Blind humans using ultrasonic mobility aids have achieved excellent navigation. First, we look at the quality of ultrasonic sensing and its suitability for navigation. Then we describe examples from our research into navigation. The paper finishes with a description of current work on corridor following.