Since 1969 a series of three bridges connect the islands Storøya and Hallvardøya in the Efjord in North Norway with the mainland. Several times a day powerful tidal currents flow between the islands. The longest bridge, the suspension bridge between the mainland and Storøya is 551 m long and has 15 spans with a maximum height of 18 m above the sea. The second bridge, between Storøya and Hallvardøya, is the smallest: 143 m long and 15 m above the sea. The third bridge connects Hallvardøya again with the mainland and is 162 m long. The mountain on Storøya. looks like a crater, worn away or fallen down on one side.