This Marine Energy Technology Roadmap, jointly developed by the Energy Technologies Institute (ETI) and the UK Energy Research Centre (UKERC) represents a major update to the ETI/UKERC 2010 Marine Energy Technology Roadmap, a document created to identify and prioritise the key technology and deployment issues faced by the marine renewable energy sector in the UK. This update has primarily been created to reflect the changes and advancements within the marine energy sector that have taken place since 2010, but it also recognises the engineering challenges that remain and that must be overcome to enable the industry to progress rapidly to early array deployments.