Provision of maintenance and inspections of all structural works on the offshore substation, its jacket foundation, and the wind turbine generators' monopile foundations in offshore wind farm Nordsee One. The initial contract period shall be five years, commencing 01.11.2017. Earlier commencement (01.11.2016) and extension for another five years term are optional. The Structural Services will include the provision of all required tools, equipment and personnel with the required qualifications. Onshore facilities and access logistics (i.e. crew vessel) will be provided by the contracting entity in / out off the port of Norddeich, Germany. Spare parts will be made available by the contracting entity.