A 2nd generation, contra-rotating marine current turbine has been developed by the Energy Systems Research Unit at the University of Strathclyde. This system can be tuned to extract energy over a wide range of water depths by “flying” a neutrally-buoyant device from a flexible, tensioned mooring. After successful proof of concept turbine trials, the development programme has moved on to investigate the performance of a scaled prototype system comprising of a dual rotor, contra-rotating turbine directly coupled to a submersible contra-rotating generator; and held on station via a gravity based tensioned mooring system. The turbine/generator assembly was initially tested in a towing tank, before the entire system underwent sea trials initially at the Kyles of Bute in the River Clyde Estuary before being deployed in eth Sound of Islay of eth West Coast of Scotland. An investigation into turbine wake development (an area in which it is hoped that the contra-rotating turbine will have uniquely beneficial properties) has recently begun. Small single-rotor model turbines have been deployed in a flume. Trends observed so far are in accordance with those observed by other researchers.