Lardin Sandaun (tsohon yankin na Yammacin Sepik ) shi ne lardin mafi arewa maso yamma na Papua New Guinea . Ya mamaye yanki na 35,920 km 2 kuma tana da yawan jama'a 248,411 (ƙidayar shekara ta 2011). Babban birni ne a Vanimo . A watan Yulin shekara ta 1998 yankin da ke kusa da garin Aitape ya sami mummunar tsunami sakamakon girgizar kasa mai karfin lamba 7.0 wanda ya kashe mutane sama da 2,000. Kauyuka biyar da ke gabar yamma ta gabar Vanimo zuwa kan Iyakokin Kasa da Kasa su ne; Lido, Waromo, Yako, Musu da Wutung. Sandaun kalma ce ta Tok Pisin da aka samo daga Ingilishi "sun down," tunda lardin yana can yamma da ƙasar, inda rana take faɗuwa. Akwai hudu gundumomi a lardin. Kowane yanki yana da yanki ɗaya ko fiye na Levelananan Hukumomi (LLG). Don dalilan kidaya, an raba yankunan LLG zuwa anguwanni da kuma wadanda aka rarraba su zuwa sashin kidaya. An gudanar da lardin ne ta hanyar mulkin mallaka na gari, karkashin jagorancin Firayim Minista, daga shekara ta 1978 zuwa shekara ta 1995.