Reloncaví Sound or Seno de Reloncaví is a body of water located immediately south of Puerto Montt, Chile. It is the place where the Intermediate Depression falls into the Pacific Ocean. There are several islands in the sound including Tenglo Island, Maillén Island and Huar Island. The Puluqui Island and Queulín Island separate it from the Gulf of Ancud.
The Carretera Austral runs along the eastern shore of the sound, but is interrupted in the area where the Reloncaví Estuary opens into this wide sound. Located in this same area is the Alerce Andino National Park, home to ancient alerce trees.
Coordinates: 41°42′00″S 72°50′00″W / 41.7°S 72.8333°W