The Vefsnfjord is a fjord in the Helgeland traditional district of Nordland county, Norway. It is about 51 kilometres (32 mi) long, reaching a maximum depth of about −440 metres (−1,440 ft). The fjord flows through the municipalities of Alstahaug, Leirfjord, and Vefsn. The fjord begins at Tjøtta, south of the island of Alsten and meets Leirfjord at Sundøy before turning to the south as it proceeds inland to Mosjøen.