Swinley Forest is a large expanse of Crown Estate woodland mainly within the civil parishes of Windlesham in Surrey and Winkfield and Crowthorne in Berkshire, England.
Situated to the south-west of Windsor Great Park, the forest stretches from Bracknell, in the north, to Bagshot, in the south. It is owned and managed by the Crown Estate and comprises over 2,600 acres (11 km2) of woodland across gently undulating hills. Although now mostly a modern plantation of Scots Pines, the area was once part of Windsor Forest. Swinley Forest includes Crowthorne Woods around Caesar's Camp between the Nine Mile Ride and Crowthorne; Swinley Park between Forest Park and the B3017; Bagshot Heath just west of Bagshot; and Swinley Woods around Kings Ride between the B3017 and South Ascot. Much of the woods cover what used to be moorland as indicated by the names of some of the hills, such as Broadmoor, Owlsmoor, Wishmoor, Gormoor, Whitmoor and Englemoor (now Englemere).
Swinley Park once surrounded Swinley Lodge where the King kept the Royal Staghounds in Georgian times. It was at the centre of Swinley Walke, one of the sub-divisions of Windsor Forest.
There are a number of late 18th century redoubts scattered throughout the forest. These defensive earth fortifications were built here not as working defences but as training grounds to carry out military exercises in the buildup to the Napoleonic Wars.