Skarnsund or Skarnsundet is a strait in the Trondheimsfjord connecting the inner section, Beitstadfjord, with the outer section. The wide Skarnsund is located in the municipality of Inderøy. On the northeastern side of the strait is the village of Vangshylla and on the southwestern side is the villages of Venneshamn and Kjerringvik (this side is the Mosvik area of Inderøy). The strait has a strong tidal current with a maelstrom.