In cognitive radio networks, multi-hop communication with efficient routing can improve the connectivity and spectrum efficiency for cognitive users. Many routing algorithms have been proposed, but they may provide unnecessarily long routing paths as the existence of primary users and especially their locations have not been explicitly taken into consideration. In this paper, we investigate distributed routing in cognitive radio networks based on the location information of the primary users. The main idea is to navigate the routing path to avoid large interference to the primary users. We introduce a novel concept of guide strip as the navigation direction for routing. This guide strip is determined based on the visibility graph, which ensures a short packet travel distance, while the width of the guide strip is selected to guarantee a predefined successful routing probability. Simulation results demonstrate that the proposed distributed routing algorithm provides performance close to the globally optimal one.