Abstract The placing of wind turbines offshore is likely to lead to developments of the technology as far-reaching as those which turned the crude onshore machines of the early 1980s into the elegant giants of today. This article discusses the acute need of development of offshore wind energy converting systems. The development of different design techniques and the economics of these systems have been reviewed in detail. The accurate wind forecasting methods, data collecting techniques and the need for site investigations have also been highlighted. Cost drivers differ offshore, with large projects of 50 MW+ and a premium on high reliability, efficient access and as much self-maintainability as possible. Designs need to be very well proven before being mass-installed offshore. Turbine technology therefore lags somewhere behind where it would optimally be, as the proving is done onshore. In the short term, technical innovation tends to focus on non-turbine aspects: support structure, foundations, installation and maintenance equipment and methods, and machine diagnosis and health check systems. However, the pressure to reduce turbine cost continues unabated. In the future, improvements will come about naturally through more efficient procurement and production methods, but there are also clues as to the direction that designs will take. Onshore, noise sensitivities impose limits on what can be achieved, but offshore there is no such limit. Tip speeds therefore can be expected to rise. Direct drive generators removing the need for transmission gearboxes offer the prospect of simplicity and high reliability. Although the direct drive generator turbine has 18% higher initial cost, its lower operation and maintenance requirement narrows this difference so that the all-up lifetime cost is found to be similar.