Diamond Tree, Karri tree in Manjimup, Western Australia, Australia

The Diamond Tree is a giant karri tree 10 km south of Manjimup on the South Western Highway. Its pale grey-brown trunk is studded with rusty steel rods and brackets, and a wooden viewing platform built in 1939 sits 49 metres up. The tree stands 51 metres tall.

From 1941 to 1973, forest rangers used this tree as an observation post during summer months to detect early signs of bushfires. This role made it a critical part of the region's forest surveillance system.

The name Diamond Tree comes from a diamond-shaped blaze cut into the trunk to mark the route of the fire lookout. The tree is one of three karri lookout trees in the Southern Forests, alongside the Gloucester Tree and the Dave Evans Bicentennial Tree, and its rusted steel climbing rods and brackets remain visible on the trunk.

Access to the climbing structure closed in 2019 for safety reasons, but the site offers walking trails and picnic areas to explore on foot. Visitors can wander the grounds and view the tree from ground level.

The platform sits 49 metres up, but the German Wikipedia gives the tree's height as 51 metres and the English article about 54; the steel rods visible on the trunk are the remains of the climbing route. The platform was the oldest wooden fire look-out still in use until its closure in 2019.