Abstract: A swivel-based mooring device is disclosed for use with marine energy devices, aquaculture systems, and port or harbor infrastructure, the device being configured to simplify deployment and improve long-term operational reliability in dynamic marine environments. In some embodiments, the device integrates an electrical slip-ring and a fluid rotary-union or swivel-joint within a single axial structure to enable continuous transmission of electrical power and fluids while permitting relative rotation between mooring components through up to 360 degrees. In some embodiments, an integrated spring or damper mechanism is provided to absorb axial loads and dynamic tension in electrical and fluid lines without materially extracting useful energy from the coupled marine device.