A method and device is provided for accessing a target location within a branched network. The device may be passed through the working channel of a standard endoscope and includes a three-dimensional location sensor at its distal tip and an expandable extended working channel. The device has a very thin body proximal of the distal sensor such that, once the sensor is extended outside of the working channel of the endoscope, nearly all of the working channel may be used to pass tools through the extended working channel of the device.