Navy ship tank maintenance is an expensive and labor-intensive endeavor that regularly exposes maintenance crews to significant environmental and safety hazards. To address this problem, Intelligent Automation, Inc. (IAI) is developing GECKO, an agile and dexterous robot capable of cleaning, inspecting, and maintaining ship tanks. GECKO leverages key existing IAI capabilities in robotic mobility, manipulation, and autonomy. For adaptive mobility, GECKO will combine magnetic crawler technology with legged robot locomotion concepts to traverse unstructured ship tank environments. For manipulation, GECKO will leverage IAI's state-of-the-art Multi-Arm Robot Control System (MARCS) technology, currently being applied to the Navy's Advanced EOD Robotic System, to enable a remote operator to easily perform dexterous activities. For adjustable autonomy, GECKO will utilize advanced localization technology to enable point-to-point navigation and semi-autonomous manipulation behaviors to reduce task execution time and operator workload. In Phase I, a preliminary design and simulation of the GECKO system is being developed. Representative tasks will be performed using existing robot hardware. In Phase II, GECKO prototypes will 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.