Navy ship tank inspection and maintenance is an expensive and labor-intensive endeavor that exposes maintenance crews to significant environmental and safety hazards. Currently, there are no known, existing automated systems that can meet all the requirements of inspection and maintenance. To address this problem, IAI and collaborators are developing GECKO, an agile and dexterous robot capable of cleaning, inspecting, and maintaining ship tanks. GECKO leverages IAI's existing capabilities in robotic mobility, manipulation, and autonomy. For adaptive mobility, GECKO will combine magnetic crawler technology with legged robot locomotion concepts to traverse unstructured and diverse ship tank environments. For manipulation, GECKO will leverage IAI's state-of-the-art Multi-Arm Robot Control System (MARCS) technology, which is currently being applied to the Navy's Advanced EOD Robotic System and enables a remote operator to easily perform dexterous activities. For adjustable autonomy, GECKO will use advanced localization technology to enable point-to-point navigation and semi-autonomous manipulation behaviors to reduce task execution time and operator workload. A preliminary design and simulation of the versatile GECKO system has been developed, and it performs representative tasks using existing robot hardware. GECKO prototypes will now be built and tested on a variety of Navy ship tanks. The GECKO robotic maintenance system will significantly reduce Navy cost and manpower requirements, and will be applicable to the worldwide commercial shipping market.