The Stillwater Ngakawau Line (SNL), formerly the Stillwater - Westport Line (SWL) and the Ngakawau Branch, is a secondary main line, part of New Zealand's national rail network. It runs between Stillwater and Ngakawau via Westport on the West Coast of the South Island. It was one of the longest construction projects in New Zealand's history, with its first section opened in 1889 but the full line not completed until 1942.