Eysturoyartunnilin located on terrain feature Streymoy
The Eysturoyartunnilin (in English the Eysturoy Tunnel, earlier known as the Skálafjarðartunnilin) is a large  undersea road tunnel under the Tangafjørður sound in the Faroe Islands, connecting the island of Streymoy to the island of Eysturoy. It also crosses the southern part of Skálafjørður, and connects the towns of Runavík on the eastern side and Strendur on the western side of the fjord, and includes the world's first undersea roundabout in the middle of the network.  
It is the largest ever infrastructure project in the Faroe Islands. Altogether, the three-branch sub-sea tunnel measures 11.24 km (6.98 mi) long, including the roundabout. Construction costs are estimated to be around a billion DKK.[7] The roundabout features artwork, including large sculptures and light effects. The tunnel opened for traffic on 19 December 2020.