Cover navigation in complex environments is a critical challenge for autonomous robots, requiring the identification and utilization of environmental cover while maintaining efficient navigation. We propose an enhanced navigation system that enables robots to identify and utilize natural and artificial environmental features as cover, thereby minimizing exposure to potential threats. Our perception pipeline leverages LiDAR data to generate high-fidelity cover maps and potential threat maps, providing a comprehensive understanding of the surrounding environment. We train an offline reinforcement learning model using a diverse dataset collected from real-world environments, learning a robust policy that evaluates the quality of candidate actions based on their ability to maximize cover utilization, minimize exposure to threats, and reach the goal efficiently. Extensive real-world experiments demonstrate the superiority of our approach in terms of success rate, cover utilization, exposure minimization, and navigation efficiency compared to state-of-the-art methods.