The Hægebostad Tunnel is the fifth longest railway tunnel in Norway. It is located in the municipalities of Lyngdal and Hægebostad in Agder county. The 8.474 km long tunnel runs between Audnedal Station and Snartemo Station on the Sørlandet Line. It was opened in 1943 when the Sørlandet Line was extended west all the way to Moi Station. The tunnel runs through the mountains virtually the entire distance between the stations of Audnedal and Snartemo. The tunnel has a 0.2% horizontal gradient and goes straight except for a curve at entrance on the Audnedal side.