Building electricity grids out to sea implies a radical transformation of grid topologies. In time, a marine super-grid is conceivable. If growing numbers of subsea electricity cables are meshed with marine renewable, a 'greening' of such grids is also possible. Based on interview research, this paper examines one such ambitious proposal: the Northern Seas Countries Offshore Grid Initiative (NSCOGI). The Multi-Level Perspective (MLP) on technology transitions is used to evaluate progress to date. Obstacles uncovered include competing and still immature grid technology niches. There is only equivocal support from key actors within the relevant socio-technical electricity regime. National grid Transmission System Operators (TSOs) appear more interested in subsea cables to trade electricity rather than enhancing marine renewables. While the EU might be assumed to be a vital actor to support a North Sea Grid, it has only limited influence. National policy insiders and decisions matter more. This paper stresses the residual importance of the national level for offshore wind and electricity grids. A marine super-grid wired up with offshore wind-farms throughout the North Sea, is both more tentative in its emergence, but also ambiguous in its support for offshore wind. (C) 2016 Elsevier Ltd. All rights reserved.