Underwater vehicle manipulator systems (UVMS) are increasingly popular platforms for performing subsea operations that require precision manipulation. While there is high demand for fully autonomous or even semi-autonomous systems, most UVMS still require human support teams. Developing new hardware and algorithms for autonomous underwater manipulation is challenging. Simulations do not capture the full complexity of the underwater environment, and deploying a UVMS at sea for testing/validation is resource-intensive and expensive. In this paper, we present a physical testbed for underwater manipulation that bridges the gap between simulation and full field trials. The underWater Arm-Vehicle Emulator (WAVE) is a 10-degree of freedom system designed to replicate an inspection-class UVMS. WAVE includes an underwater perception sensor and has 2 operating modes: rigid or passive-mode. In passive-mode, the ROV body can pitch similar to how a dynamically-coupled underactuated UVMS without pitch control would rotate during manipulation tasks. To validate the overall design and passive pitch concept, we evaluated the testbed during underwater experiments in energetic conditions at a wave basin. To support continued research and development in underwater robotics, we make the design open-access and freely available to the community.