Work has been completed on a £1bn subsea electricity link between Caithness and Moray.
The cable will allow renewable energy generated in the far north to be sent to areas of dense population in central Scotland.
The 100-mile-long cable is capable of carrying enough electricity to power three million homes.
Project leader SSE says it is the biggest single investment in the north of Scotland network since the 1950s.
The link uses a high voltage direct current to transmit power beneath the Moray Firth to a substation at Blackhillock near Keith.
Covering an area the size of 24 football pitches, it is the largest substation in the UK.
Project leader Dave Gardner said: "The successful energisation and commissioning of the Caithness-Moray link, on time and within budget, is a significant achievement for SSEN and everyone involved in the project.
"It will support deployment of renewable energy in the north of Scotland for many years to come.
"Now an operational asset, as a responsible network owner we will closely monitor the link and associated infrastructure to ensure its continued success as an integral part of the GB transmission system."
The link is regarded as an important tool in tapping into Scotland's abundance of renewable energy sources.
It is connected to the Beatrice offshore wind farm and the Dorenell onshore farm in Caithness.
More sites in Caithness and Ross-shire are due to be connected in the next few months.