The marine renewable energy (MRE) sector is progressing from single device units to device arrays. Currently, the mooring/foundation technologies used in MRE are based on offshore oil/gas industry practices. For MRE arrays to reach commercialization, several issues need to be addressed including the hydrodynamic array layout, electrical infrastructure, operations, maintenance, control, moorings, foundations, installation and logistics. The DTOcean (The Optimal Design Tools for Ocean Energy Arrays) project is aimed at accelerating the industrial development of ocean energy power generation knowledge, and providing design tools for deploying the first generation of wave and tidal energy converter arrays. In this paper, the applicability of offshore mooring/foundation technologies for marine renewable energy (MRE) device arrays are assessed. The paper introduces the criteria which can be used to appraise technologies and approaches relevant to MRE devices. Existing mooring/foundation technologies used in the offshore industry are summarized with examples given of MRE device deployments. The guidance from certification agencies which is used for the design and analysis of mooring/foundation systems is summarized. If not addressed, the failure to optimize the design of ocean energy arrays and failure to properly understand economic, environmental, or reliability impacts of individual components could have significant consequences for the overall project and sector. The function and type of mooring and/or foundation system are determined by a number of factors including the cost, site characteristics, expected environmental loading and environmental or legislative constraints and these factors are discussed.