Four renewable energy companies which will compete for the £10m Saltire Prize have been named by Scottish ministers.
The competition was set up to encourage the development of wave and tidal energy devices in Scottish waters.
ScottishPower Renewables, Aquamarine Power, Pelamis Wave Power and MeyGen will each attempt to produce the most electricity over a two-year period, using only the power of the sea.
Projects will be launched off Lewis, in the Pentland Firth and Orkney waters.
The latest phase of the contest will run until 2017.