The Diamond Tree is a giant karri tree located 10 km south of Manjimup, Western Australia on the South Western Highway. A wooden viewing platform built in 1939 is located 49 metres up, and was the oldest wooden platform fire look-out in use until its closure in 2019. The Diamond Tree was one of three lookout trees in the Southern Forests and was used as a fire lookout every summer from 1941 to 1973. The tower was used by DEC (Department of Environment & Conservation) to support aerial surveillance from time to time.