In what is being called the UK's most challenging rural broadband project, the scheme took a significant step forward with the arrival of the cable in the Western Isles.
The specialist cable-laying ship the Rene Descartes was off the east coast of Lewis for high tide on Thursday morning to land the cable. It is the start of the project's longest subsea link - nearly 50 miles under the Minch to Ullapool.
The work forms a vital part of a £146m public investment to create a huge 745-mile land and subsea fibre network across the region.
Brendan Dick, director, BT Scotland, said: "This is an historic day for the people of the Western Isles as our subsea cable is landed at Stornoway and fibre broadband in the isles begins turning into reality."
On the Outer Hebrides more than 60 miles of land-based broadband 'backbone' is to be built between Stornoway on Lewis in the north of the archipelago to Carnan on South Uist.
From there a second subsea link will stretch more than 35 miles to Dunvegan on Skye. In addition there will be island-to-island subsea cables.
The cabling forms part of the £146m Highlands and Islands project being led by Highlands and Islands Enterprise (HIE). Funding partners include the Scottish Government, HIE, and Broadband Delivery UK (BDUK). BT, the selected private sector partner who is rolling out the open access fibre network, is investing £19 million in the area.