Viðoy (Faroese pronunciation: [ˈviːjɔɪ], Danish: Viderø) is the northernmost island in the Faroe Islands, located east of Borðoy to which it is linked via a causeway.

The island is connected by a road causeway from Hvannasund to Norðdepil on Borðoy, and a bus service from Klaksvík runs across the causeway to the island.

[2] The island's northern and eastern coast has been identified as an Important Bird Area by BirdLife International because of its significance as a breeding site for seabirds, especially European storm petrels (500 pairs), black-legged kittiwakes (5300 pairs), Atlantic puffins (25,000 pairs), common guillemots (6700 individuals) and black guillemots (200 pairs).

[3] Viðoy has eleven mountains, of which Villingadalsfjall is the northernmost peak in the Faroes.

The north coast also has the Enniberg cliff, which at 750 m is the second-highest sea-cliff in Europe (after Hornelen, in Norway).