Many civil applications and exploration activities are impractical for humans such as underground infrastructure inspection (e.g., underground pipes and Cave exploration) due to the space factor for humans to inspect, safety conditions, and dangerous environment. Our mission is to send a drone to survey the environments without any risk to human safety. Such a mission would require sensing the environment properly, navigation through a completely unknown path, obstacle avoidance, recording findings, and returning safely. The above tasks need to be performed with a zero wireless connection to a base station. A number of factors need to be considered in addressing such challenging mission: navigation decisions are made on the drone, no support from more powerful hardware, limited to what is available on the drone, cannot rely on modern DNN solutions for navigation, maneuver in tight areas, less power for processing and flight controls, and limited flight time.