We describe an ocean hydrostatic dynamical core implemented in Oceananigans optimized for Graphical Processing Unit (GPU) architectures. On 64 A100 GPUs, equivalent to 16 computational nodes in current state-of-the-art supercomputers, our dynamical core can simulate a decade of near-global ocean dynamics per wall-clock day at an 8-km horizontal resolution; a resolution adequate to resolve the ocean’s mesoscale eddy field. Such efficiency, achieved with relatively modest hardware resources, suggests that climate simulations on GPUs can incorporate fully eddy-resolving ocean models. This removes a major source of systematic bias in current IPCC coupled model projections, the parameterization of ocean eddies, and represents a major advance in climate modeling. We discuss the computational strategies, focusing on GPU-specific optimization and numerical implementation details that enable such high performance.