British Isles fixed sea connections

The Orkney tunnel is a suggested undersea road tunnel from Orkney to Caithness in the Scottish mainland. The expected length will be 15 - 16 km.

The tunnel, if constructed, is assumed to make landfall at South Ronaldsay. In 2005, the tunnel was discussed, and then $100 million was mentioned. There have not been much discussion since 2005.

There are also plans to connect Orkney Mainland and Shapinsay.

With recent developments of the renewable industry at the Pentland Firth, the idea of the tunnel has lost ground, through there have been much discussions of the construction of the bridge over the Pentland Tidal Array.