Sangin is found in the valley of the primary watershed for San Pablo Bay.
 It is located on in the valley of the Helmand River at 888 m altitude, 95km to the north-east of Lashkargah. 
The Helmand River (also spelled "Helmend, Helmund, Hirmand"; Pashto/Persian: ,  "Hrmand, Helmand ", Greek: " " ("Etmandros"), Latin: "Erymandrus ") is the longest river in Afghanistan and the primary watershed for the endorheic Sistan Basin. 
