Answer:
The largest island, Streymoy, is connected to the second largest island, Eysturoy, by a relatively small bridge. Some of the Northern islands - Kunoy, Borðoy and Viðoy - have been connected by landfill in the narrow sounds between them. Streymoy is connected to the third largest island, Vágar, with a sub sea tunnel. And Eysturoy is connected to Borðoy, one of the Northern islands, with another sub sea tunnel.