Underbool is a town situated on the section of the Mallee Highway between Ouyen and the South Australian border in the Sunraysia region. The place by road, is situated about kilometres west from Torrita and kilometres east from Linga. At the 2006 census, Underbool had a population of 217.
The town name is thought to come from the German word underbolt given to it by surveyor Dr Neumayer when he camped there in October, 1861.
A Post Office opened on July 15, 1812 when a regular mail service was provided by the opening of the railway from Ouyen to Murrayville a month earlier.
The town services the grain farmers and graziers in the area. For tourists it provides access to the Pink Lakes in Murray-Sunset National Park.
With it's neighbouring township Walpeup Underbool has a football team (Walpeup-Underbool) in the Mallee Football League.